TY - JOUR AB - 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. AU - Franco, D. G. AU - Avalos, R. AU - Hafner, D. AU - Modic, Kimberly A AU - Prots, Yu AU - Stockert, O. AU - Hoser, A. AU - Moll, P. J.W. AU - Brando, M. AU - Aligia, A. A. AU - Geibel, C. ID - 15003 IS - 5 JF - Physical Review B SN - 2469-9950 TI - Frustrated magnetism in octahedra-based Ce6 Ni6 P17 VL - 109 ER - TY - JOUR AB - 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. AU - Shekhter, A. AU - Mcdonald, R. D. AU - Ramshaw, B. J. AU - Modic, Kimberly A ID - 13257 IS - 3 JF - Physical Review B SN - 2469-9950 TI - Magnetotropic susceptibility VL - 108 ER - TY - JOUR AB - 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. AU - Nauman, Muhammad AU - Hussain, Tayyaba AU - Choi, Joonyoung AU - Lee, Nara AU - Choi, Young Jai AU - Kang, Woun AU - Jo, Younjung ID - 10735 IS - 13 JF - Journal of physics: Condensed matter TI - Low-field magnetic anisotropy of Sr2IrO4 VL - 34 ER - TY - JOUR AB - 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. AU - Aguilera, Esteban AU - Clerc, Marcel G. AU - Zambra, Valeska ID - 11343 JF - Nonlinear Dynamics KW - Electrical and Electronic Engineering KW - Applied Mathematics KW - Mechanical Engineering KW - Ocean Engineering KW - Aerospace Engineering KW - Control and Systems Engineering SN - 0924-090X TI - Vortices nucleation by inherent fluctuations in nematic liquid crystal cells VL - 108 ER - TY - JOUR AB - 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 AU - Nirwan, Jorabar Singh AU - Lou, Shan AU - Hussain, Saqib AU - Nauman, Muhammad AU - Hussain, Tariq AU - Conway, Barbara R. AU - Ghori, Muhammad Usman ID - 10584 IS - 1 JF - Micromachines KW - surface texture KW - electrically tunable lens KW - materials KW - hypromellose KW - surface topography KW - surface roughness KW - pharmaceutical tablet KW - variable focus imaging TI - Electrically tunable lens (ETL) - based variable focus imaging system for parametric surface texture analysis of materials VL - 13 ER - TY - JOUR AB - 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. AU - Nauman, Muhammad AU - Kiem, Do Hoon AU - Lee, Sungmin AU - Son, Suhan AU - Park, J-G AU - Kang, Woun AU - Han, Myung Joon AU - Jo, Youn Jung ID - 9282 IS - 3 JF - 2D Materials KW - Mechanical Engineering KW - General Materials Science KW - Mechanics of Materials KW - General Chemistry KW - Condensed Matter Physics SN - 2053-1583 TI - Complete mapping of magnetic anisotropy for prototype Ising van der Waals FePS3 VL - 8 ER - TY - JOUR AB - 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. AU - Modic, Kimberly A AU - McDonald, Ross D. AU - Ruff, J.P.C. AU - Bachmann, Maja D. AU - Lai, You AU - Palmstrom, Johanna C. AU - Graf, David AU - Chan, Mun K. AU - Balakirev, F.F. AU - Betts, J.B. AU - Boebinger, G.S. AU - Schmidt, Marcus AU - Lawler, Michael J. AU - Sokolov, D.A. AU - Moll, Philip J.W. AU - Ramshaw, B.J. AU - Shekhter, Arkady ID - 8673 JF - Nature Physics SN - 17452473 TI - Scale-invariant magnetic anisotropy in RuCl3 at high magnetic fields VL - 17 ER - TY - JOUR AB - 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. AU - Dar, M. S. AU - Akram, Khush Bakhat AU - Sohail, Ayesha AU - Arif, Fatima AU - Zabihi, Fatemeh AU - Yang, Shengyuan AU - Munir, Shamsa AU - Zhu, Meifang AU - Abid, M. AU - Nauman, Muhammad ID - 9569 IS - 35 JF - RSC Advances TI - Heat induction in two-dimensional graphene–Fe3O4 nanohybrids for magnetic hyperthermia applications with artificial neural network modeling VL - 11 ER - TY - JOUR AB - 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. AU - Lu, Yuzheng AU - Arshad, Naila AU - Irshad, Muhammad Sultan AU - Ahmed, Iftikhar AU - Ahmad, Shafiq AU - Alshahrani, Lina Abdullah AU - Yousaf, Muhammad AU - Sayed, Abdelaty Edrees AU - Nauman, Muhammad ID - 10586 IS - 12 JF - Crystals TI - Fe2O3 nanoparticles deposited over self-floating facial sponge for facile interfacial seawater solar desalination VL - 11 ER - TY - JOUR AB - 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. AU - Hartstein, Máté AU - Hsu, Yu Te AU - Modic, Kimberly A AU - Porras, Juan AU - Loew, Toshinao AU - Tacon, Matthieu Le AU - Zuo, Huakun AU - Wang, Jinhua AU - Zhu, Zengwei AU - Chan, Mun K. AU - Mcdonald, Ross D. AU - Lonzarich, Gilbert G. AU - Keimer, Bernhard AU - Sebastian, Suchitra E. AU - Harrison, Neil ID - 7942 JF - Nature Physics SN - 17452473 TI - Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-Tc superconductors VL - 16 ER - TY - GEN AB - 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. AU - Hartstein, Mate AU - Hsu, Yu-Te AU - Modic, Kimberly A AU - Porras, Juan AU - Loew, Toshinao AU - Le Tacon, Matthieu AU - Zuo, Huakun AU - Wang, Jinhua AU - Zhu, Zengwei AU - Chan, Mun AU - McDonald, Ross AU - Lonzarich, Gilbert AU - Keimer, Bernhard AU - Sebastian, Suchitra AU - Harrison, Neil ID - 9708 TI - Accompanying dataset for 'Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-Tc superconductors' ER -