@misc{21174, abstract = {UTe2 exhibits the remarkable phenomenon of re-entrant superconductivity, whereby the zero-resistance state reappears above 40 tesla after being suppressed with a field of around 10 tesla. One potential pairing mechanism, invoked in the related re-entrant superconductors UCoGe and URhGe, involves transverse fluctuations of a ferromagnetic order parameter. However, the requisite ferromagnetic order - present in both UCoGe and URhGe - is absent in UTe2, and magnetization measurements show no sign of strong fluctuations. Here, we measure the magnetotropic susceptibility of UTe2 across two field-angle planes. This quantity is sensitive to the magnetic susceptibility in a direction transverse to the applied magnetic field - a quantity that is not accessed in conventional magnetization measurements. We observe a very large decrease in the magnetotropic susceptibility over a broad range of field orientations, indicating a large increase in the transverse magnetic susceptibility. The three superconducting phases of UTe2, including the high-field re-entrant phase, surround this region of enhanced susceptibility in the field-angle phase diagram. The strongest transverse susceptibility is found near the critical end point of the high-field metamagnetic transition, suggesting that quantum critical fluctuations of a field-induced magnetic order parameter may be responsible for the large transverse susceptibility, and may provide a pairing mechanism for field-induced superconductivity in UTe2.}, author = {Modic, Kimberly A}, keywords = {transverse magnetic susceptibility, magnetotropic, superconductivity, magnetic fluctuations}, publisher = {Institute of Science and Technology Austria}, title = {{Research data for "Giant transverse magnetic fluctuations at the edge of re-entrant superconductivity in UTe2"}}, doi = {10.15479/AT-ISTA-21174}, year = {2026}, } @article{20453, abstract = {Magnetotropic susceptibility is the thermodynamic coefficient that maps the curvature of free energy with respect to an applied magnetic field orientation, providing a means to quantify the magnetic anisotropy of a crystal. In this context, non-linear magnetic torque behavior has been reported in FePS3, motivating the investigation of similar non-linear characteristics in its magnetotropic susceptibility. In this work, we derive the non-linear magnetotropic susceptibility expressions for FePS3 in both ac*-and bc*-planes using complementary approaches: by taking the first derivative of torque and through the formal calculation of the magnetotropic susceptibility. Higher-order terms in the magnetization are included, and the final equations are obtained by applying symmetry constraints imposed by the C2h point group of the material. We analyze the behavior of the resulting non-linear expressions and identify the contributions of each parameter. Our theoretical results show good agreement with preliminary, unpublished experimental data, offering meaningful guidance for ongoing and future experimental work.}, author = {Farooq, Hamza and Nauman, Muhammad}, issn = {1361-648X}, journal = {Journal of Physics Condensed Matter}, number = {40}, publisher = {IOP Publishing}, title = {{Non-linear magnetotropic susceptibility in FePS3}}, doi = {10.1088/1361-648X/ae0913}, volume = {37}, year = {2025}, } @article{18654, abstract = {We compute the rotational anisotropy of the free energy of 𝛼−RuCl3 in an external magnetic field. This quantity, known as the magnetotropic susceptibility, 𝑘, relates to the second derivative of the free energy with respect to the angle of rotation. We have used approximation-free, auxiliary-field quantum Monte Carlo simulations for a realistic model of 𝛼−RuCl3 and optimized the path integral to alleviate the negative sign problem. This allows us to reach temperatures down to 30K—an energy scale below the dominant Kitaev coupling. We demonstrate that the magnetotropic spin susceptibility in this model of 𝛼−RuCl3 displays scaling behavior 𝑘=𝑇⁢𝑓⁡(𝐵/𝑇) at high temperatures. Once the uniform susceptibility departs from the Curie law (i.e., at the energy scale of the exchange interactions), it appears to transition to an emergent scalinglike behavior, characterized by a different function 𝑓 at lower temperatures, stemming from the locality of torque fluctuations. We observe a remarkable numerical match between experiment and simulations and we also find qualitative agreement with the pure Kitaev model. In comparison, for the XXZ Heisenberg Hamiltonian, the scaling 𝑘=𝑇⁢𝑓⁡(𝐵/𝑇) breaks down at a temperature scale where the uniform spin susceptibility deviates from the Curie law and never reemerges at low temperatures.}, author = {Sato, Toshihiro and Ramshaw, B. J. and Modic, Kimberly A and Assaad, Fakher F.}, issn = {2469-9969}, journal = {Physical Review B}, number = {20}, publisher = {American Physical Society}, title = {{Scale-invariant magnetic anisotropy in α-RuCl3: A quantum Monte Carlo study}}, doi = {10.1103/PhysRevB.110.L201114}, volume = {110}, year = {2024}, } @article{15003, abstract = {Magnetic frustration allows to access novel and intriguing properties of magnetic systems and has been explored mainly in planar triangular-like arrays of magnetic ions. In this work, we describe the phosphide Ce6Ni6P17, where the Ce+3 ions accommodate in a body-centered cubic lattice of Ce6 regular octahedra. From measurements of magnetization, specific heat, and resistivity, we determine a rich phase diagram as a function of temperature and magnetic field in which different magnetic phases are found. Besides clear evidence of magnetic frustration is obtained from entropy analysis. At zero field, a second-order antiferromagnetic transition occurs at TN1≈1 K followed by a first-order transition at TN2≈0.45 K. With magnetic field new magnetic phases appear, including a weakly first-order transition which ends in a classical critical point and a third magnetic phase. We also study the exact solution of the spin-1/2 Heisenberg model in an octahedron which allows us a qualitative understanding of the phase diagram and compare with the experimental results.}, author = {Franco, D. G. and Avalos, R. and Hafner, D. and Modic, Kimberly A and Prots, Yu and Stockert, O. and Hoser, A. and Moll, P. J.W. and Brando, M. and Aligia, A. A. and Geibel, C.}, issn = {2469-9969}, journal = {Physical Review B}, number = {5}, publisher = {American Physical Society}, title = {{Frustrated magnetism in octahedra-based Ce6 Ni6 P17}}, doi = {10.1103/PhysRevB.109.054405}, volume = {109}, year = {2024}, } @article{13257, abstract = {The magnetotropic susceptibility is the thermodynamic coefficient associated with the rotational anisotropy of the free energy in an external magnetic field and is closely related to the magnetic susceptibility. It emerges naturally in frequency-shift measurements of oscillating mechanical cantilevers, which are becoming an increasingly important tool in the quantitative study of the thermodynamics of modern condensed-matter systems. Here we discuss the basic properties of the magnetotropic susceptibility as they relate to the experimental aspects of frequency-shift measurements, as well as to the interpretation of those experiments in terms of the intrinsic properties of the system under study.}, author = {Shekhter, A. and Mcdonald, R. D. and Ramshaw, B. J. and Modic, Kimberly A}, issn = {2469-9969}, journal = {Physical Review B}, number = {3}, publisher = {American Physical Society}, title = {{Magnetotropic susceptibility}}, doi = {10.1103/PhysRevB.108.035111}, volume = {108}, year = {2023}, } @article{10584, abstract = {Electrically tunable lenses (ETLs) are those with the ability to alter their optical power in response to an electric signal. This feature allows such systems to not only image the areas of interest but also obtain spatial depth perception (depth of field, DOF). The aim of the present study was to develop an ETL-based imaging system for quantitative surface analysis. Firstly, the system was calibrated to achieve high depth resolution, warranting the accurate measurement of the depth and to account for and correct any influences from external factors on the ETL. This was completed using the Tenengrad operator which effectively identified the plane of best focus as demonstrated by the linear relationship between the control current applied to the ETL and the height at which the optical system focuses. The system was then employed to measure amplitude, spatial, hybrid, and volume surface texture parameters of a model material (pharmaceutical dosage form) which were validated against the parameters obtained using a previously validated surface texture analysis technique, optical profilometry. There were no statistically significant differences between the surface texture parameters measured by the techniques, highlighting the potential application of ETL-based imaging systems as an easily adaptable and low-cost alternative surface texture analysis technique to conventional microscopy techniques}, author = {Nirwan, Jorabar Singh and Lou, Shan and Hussain, Saqib and Nauman, Muhammad and Hussain, Tariq and Conway, Barbara R. and Ghori, Muhammad Usman}, issn = {2072-666X}, journal = {Micromachines}, keywords = {surface texture, electrically tunable lens, materials, hypromellose, surface topography, surface roughness, pharmaceutical tablet, variable focus imaging}, number = {1}, publisher = {MDPI}, title = {{Electrically tunable lens (ETL) - based variable focus imaging system for parametric surface texture analysis of materials}}, doi = {10.3390/mi13010017}, volume = {13}, year = {2022}, } @article{10735, abstract = {Magnetic anisotropy in strontium iridate (Sr2IrO4) is essential because of its strong spin–orbit coupling and crystal field effect. In this paper, we present a detailed mapping of the out-of-plane (OOP) magnetic anisotropy in Sr2IrO4 for different sample orientations using torque magnetometry measurements in the low-magnetic-field region before the isospins are completely ordered. Dominant in-plane anisotropy was identified at low fields, confirming the b axis as an easy magnetization axis. Based on the fitting analysis of the strong uniaxial magnetic anisotropy, we observed that the main anisotropic effect arises from a spin–orbit-coupled magnetic exchange interaction affecting the OOP interaction. The effect of interlayer exchange interaction results in additional anisotropic terms owing to the tilting of the isospins. The results are relevant for understanding OOP magnetic anisotropy and provide a new way to analyze the effects of spin–orbit-coupling and interlayer magnetic exchange interactions. This study provides insight into the understanding of bulk magnetic, magnetotransport, and spintronic behavior on Sr2IrO4 for future studies.}, author = {Nauman, Muhammad and Hussain, Tayyaba and Choi, Joonyoung and Lee, Nara and Choi, Young Jai and Kang, Woun and Jo, Younjung}, issn = {1361-648X}, journal = {Journal of physics: Condensed matter}, number = {13}, publisher = {IOP Publishing}, title = {{Low-field magnetic anisotropy of Sr2IrO4}}, doi = {10.1088/1361-648X/ac484d}, volume = {34}, year = {2022}, } @article{11343, abstract = {Multistable systems are characterized by exhibiting domain coexistence, where each domain accounts for the different equilibrium states. In case these systems are described by vectorial fields, domains can be connected through topological defects. Vortices are one of the most frequent and studied topological defect points. Optical vortices are equally relevant for their fundamental features as beams with topological features and their applications in image processing, telecommunications, optical tweezers, and quantum information. A natural source of optical vortices is the interaction of light beams with matter vortices in liquid crystal cells. The rhythms that govern the emergence of matter vortices due to fluctuations are not established. Here, we investigate the nucleation mechanisms of the matter vortices in liquid crystal cells and establish statistical laws that govern them. Based on a stochastic amplitude equation, the law for the number of nucleated vortices as a function of anisotropy, voltage, and noise level intensity is set. Experimental observations in a nematic liquid crystal cell with homeotropic anchoring and a negative anisotropic dielectric constant under the influence of a transversal electric field show a qualitative agreement with the theoretical findings.}, author = {Aguilera, Esteban and Clerc, Marcel G. and Zambra, Valeska}, issn = {1573-269X}, journal = {Nonlinear Dynamics}, keywords = {Electrical and Electronic Engineering, Applied Mathematics, Mechanical Engineering, Ocean Engineering, Aerospace Engineering, Control and Systems Engineering}, pages = {3209--3218}, publisher = {Springer Nature}, title = {{Vortices nucleation by inherent fluctuations in nematic liquid crystal cells}}, doi = {10.1007/s11071-022-07396-5}, volume = {108}, year = {2022}, } @article{10586, abstract = {A facile approach for developing an interfacial solar evaporator by heat localization of solar-thermal energy conversion at water-air liquid composed by in-situ polymerization of Fe2O3 nanoparticles (Fe2O3@PPy) deposited over a facial sponge is proposed. The demonstrated system consists of a floating solar receiver having a vertically cross-linked microchannel for wicking up saline water. The in situ polymerized Fe2O3@PPy interfacial layer promotes diffuse reflection and its rough black surface allows Omni-directional solar absorption (94%) and facilitates efficient thermal localization at the water/air interface and offers a defect-rich surface to promote heat localization (41.9 °C) and excellent thermal management due to cellulosic content. The self-floating composite foam reveals continuous vapors generation at a rate of 1.52 kg m−2 h−1 under one 1 kW m−2 and profound evaporating efficiency (95%) without heat losses that dissipates in its surroundings. Indeed, long-term evaporation experiments reveal the negligible disparity in continuous evaporation rate (33.84 kg m−2/8.3 h) receiving two sun solar intensity, and ensures the stability of the device under intense seawater conditions synchronized with excellent salt rejection potential. More importantly, Raman spectroscopy investigation validates the orange dye rejection via Fe2O3@PPy solar evaporator. The combined advantages of high efficiency, self-floating capability, multimedia rejection, low cost, and this configuration are promising for producing large-scale solar steam generating systems appropriate for commercial clean water yield due to their scalable fabrication.}, author = {Lu, Yuzheng and Arshad, Naila and Irshad, Muhammad Sultan and Ahmed, Iftikhar and Ahmad, Shafiq and Alshahrani, Lina Abdullah and Yousaf, Muhammad and Sayed, Abdelaty Edrees and Nauman, Muhammad}, issn = {2073-4352}, journal = {Crystals}, number = {12}, publisher = {MDPI}, title = {{Fe2O3 nanoparticles deposited over self-floating facial sponge for facile interfacial seawater solar desalination}}, doi = {10.3390/cryst11121509}, volume = {11}, year = {2021}, } @article{8673, abstract = {In RuCl3, inelastic neutron scattering and Raman spectroscopy reveal a continuum of non-spin-wave excitations that persists to high temperature, suggesting the presence of a spin liquid state on a honeycomb lattice. In the context of the Kitaev model, finite magnetic fields introduce interactions between the elementary excitations, and thus the effects of high magnetic fields that are comparable to the spin-exchange energy scale must be explored. Here, we report measurements of the magnetotropic coefficient—the thermodynamic coefficient associated with magnetic anisotropy—over a wide range of magnetic fields and temperatures. We find that magnetic field and temperature compete to determine the magnetic response in a way that is independent of the large intrinsic exchange-interaction energy. This emergent scale-invariant magnetic anisotropy provides evidence for a high degree of exchange frustration that favours the formation of a spin liquid state in RuCl3.}, author = {Modic, Kimberly A and McDonald, Ross D. and Ruff, J.P.C. and Bachmann, Maja D. and Lai, You and Palmstrom, Johanna C. and Graf, David and Chan, Mun K. and Balakirev, F.F. and Betts, J.B. and Boebinger, G.S. and Schmidt, Marcus and Lawler, Michael J. and Sokolov, D.A. and Moll, Philip J.W. and Ramshaw, B.J. and Shekhter, Arkady}, issn = {1745-2481}, journal = {Nature Physics}, pages = {240--244}, publisher = {Springer Nature}, title = {{Scale-invariant magnetic anisotropy in RuCl3 at high magnetic fields}}, doi = {10.1038/s41567-020-1028-0}, volume = {17}, year = {2021}, } @article{9282, abstract = {Several Ising-type magnetic van der Waals (vdW) materials exhibit stable magnetic ground states. Despite these clear experimental demonstrations, a complete theoretical and microscopic understanding of their magnetic anisotropy is still lacking. In particular, the validity limit of identifying their one-dimensional (1-D) Ising nature has remained uninvestigated in a quantitative way. Here we performed the complete mapping of magnetic anisotropy for a prototypical Ising vdW magnet FePS3 for the first time. Combining torque magnetometry measurements with their magnetostatic model analysis and the relativistic density functional total energy calculations, we successfully constructed the three-dimensional (3-D) mappings of the magnetic anisotropy in terms of magnetic torque and energy. The results not only quantitatively confirm that the easy axis is perpendicular to the ab plane, but also reveal the anisotropies within the ab, ac, and bc planes. Our approach can be applied to the detailed quantitative study of magnetism in vdW materials.}, author = {Nauman, Muhammad and Kiem, Do Hoon and Lee, Sungmin and Son, Suhan and Park, J-G and Kang, Woun and Han, Myung Joon and Jo, Youn Jung}, issn = {2053-1583}, journal = {2D Materials}, keywords = {Mechanical Engineering, General Materials Science, Mechanics of Materials, General Chemistry, Condensed Matter Physics}, number = {3}, publisher = {IOP Publishing}, title = {{Complete mapping of magnetic anisotropy for prototype Ising van der Waals FePS3}}, doi = {10.1088/2053-1583/abeed3}, volume = {8}, year = {2021}, } @article{9569, abstract = {We report the synthesis and characterization of graphene functionalized with iron (Fe3+) oxide (G-Fe3O4) nanohybrids for radio-frequency magnetic hyperthermia application. We adopted the wet chemical procedure, using various contents of Fe3O4 (magnetite) from 0–100% for making two-dimensional graphene–Fe3O4 nanohybrids. The homogeneous dispersal of Fe3O4 nanoparticles decorated on the graphene surface combined with their biocompatibility and high thermal conductivity make them an excellent material for magnetic hyperthermia. The morphological and magnetic properties of the nanohybrids were studied using scanning electron microscopy (SEM) and a vibrating sample magnetometer (VSM), respectively. The smart magnetic platforms were exposed to an alternating current (AC) magnetic field of 633 kHz and of strength 9.1 mT for studying their hyperthermic performance. The localized antitumor effects were investigated with artificial neural network modeling. A neural net time-series model was developed for the assessment of the best nanohybrid composition to serve the purpose with an accuracy close to 100%. Six Nonlinear Autoregressive with External Input (NARX) models were obtained, one for each of the components. The assessment of the accuracy of the predicted results has been done on the basis of Mean Squared Error (MSE). The highest Mean Squared Error value was obtained for the nanohybrid containing 45% magnetite and 55% graphene (F45G55) in the training phase i.e., 0.44703, which is where the model achieved optimal results after 71 epochs. The F45G55 nanohybrid was found to be the best for hyperthermia applications in low dosage with the highest specific absorption rate (SAR) and mean squared error values.}, author = {Dar, M. S. and Akram, Khush Bakhat and Sohail, Ayesha and Arif, Fatima and Zabihi, Fatemeh and Yang, Shengyuan and Munir, Shamsa and Zhu, Meifang and Abid, M. and Nauman, Muhammad}, issn = {2046-2069}, journal = {RSC Advances}, number = {35}, pages = {21702--21715}, publisher = {Royal Society of Chemistry}, title = {{Heat induction in two-dimensional graphene–Fe3O4 nanohybrids for magnetic hyperthermia applications with artificial neural network modeling}}, doi = {10.1039/d1ra03428f}, volume = {11}, year = {2021}, } @article{7942, abstract = {An understanding of the missing antinodal electronic excitations in the pseudogap state is essential for uncovering the physics of the underdoped cuprate high-temperature superconductors1,2,3,4,5,6. The majority of high-temperature experiments performed thus far, however, have been unable to discern whether the antinodal states are rendered unobservable due to their damping or whether they vanish due to their gapping7,8,9,10,11,12,13,14,15,16,17,18. Here, we distinguish between these two scenarios by using quantum oscillations to examine whether the small Fermi surface pocket, found to occupy only 2% of the Brillouin zone in the underdoped cuprates19,20,21,22,23,24, exists in isolation against a majority of completely gapped density of states spanning the antinodes, or whether it is thermodynamically coupled to a background of ungapped antinodal states. We find that quantum oscillations associated with the small Fermi surface pocket exhibit a signature sawtooth waveform characteristic of an isolated two-dimensional Fermi surface pocket25,26,27,28,29,30,31,32. This finding reveals that the antinodal states are destroyed by a hard gap that extends over the majority of the Brillouin zone, placing strong constraints on a drastic underlying origin of quasiparticle disappearance over almost the entire Brillouin zone in the pseudogap regime7,8,9,10,11,12,13,14,15,16,17,18.}, author = {Hartstein, Máté and Hsu, Yu Te and Modic, Kimberly A and Porras, Juan and Loew, Toshinao and Tacon, Matthieu Le and Zuo, Huakun and Wang, Jinhua and Zhu, Zengwei and Chan, Mun K. and Mcdonald, Ross D. and Lonzarich, Gilbert G. and Keimer, Bernhard and Sebastian, Suchitra E. and Harrison, Neil}, issn = {1745-2481}, journal = {Nature Physics}, pages = {841--847}, publisher = {Springer Nature}, title = {{Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-Tc superconductors}}, doi = {10.1038/s41567-020-0910-0}, volume = {16}, year = {2020}, } @misc{9708, abstract = {This research data supports 'Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-Tc superconductors'. A Readme file for plotting each figure is provided.}, author = {Hartstein, Mate and Hsu, Yu-Te and Modic, Kimberly A and Porras, Juan and Loew, Toshinao and Le Tacon, Matthieu and Zuo, Huakun and Wang, Jinhua and Zhu, Zengwei and Chan, Mun and McDonald, Ross and Lonzarich, Gilbert and Keimer, Bernhard and Sebastian, Suchitra and Harrison, Neil}, publisher = {Apollo - University of Cambridge}, title = {{Accompanying dataset for 'Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-Tc superconductors'}}, doi = {10.17863/cam.50169}, year = {2020}, }