Article
Chemistry, Physical
Aleksei S. Komlev, Dmitriy Y. Karpenkov, Dmitry A. Kiselev, Tatiana S. Ilina, Alisa Chirkova, Radel R. Gimaev, Takamasa Usami, Tomoyasu Taniyama, Vladimir Zverev, Nikolai S. Perov
Summary: This study comprehensively characterized the nucleation and evolution of the ferromagnetic phase in the thin Fe49Rh51 film on a MgO substrate near the antiferromagnetic (AFM) to ferromagnetic (FM) phase transition, utilizing measurements of temperature, time, and magnetic field dependencies. The observed relaxation processes of magnetization indicate the nucleation of the FM phase on the film surface and its growth towards the film-substrate interface. The confirmation of FM phase growth evolution was verified through vibrational magnetometry and magnetic force microscopy methods.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Multidisciplinary Sciences
Jin Yue, Yilikal Ayino, Tristan K. Truttmann, Maria N. Gastiasoro, Eylon Persky, Alex Khanukov, Dooyong Lee, Laxman R. Thoutam, Beena Kalisky, Rafael M. Fernandes, Vlad S. Pribiag, Bharat Jalan
Summary: Using hybrid MBE, high-quality SrTiO₃ films with low defect density were obtained, and their transport properties were studied. The dominant influence of intraband scattering at the second Lifshitz transition was observed, along with the anomalous temperature dependence of the Hall scattering factor and carrier density due to the antiferrodistortive transition.
Article
Physics, Applied
Andrew W. Forbes, Niraj Bhattarai, Christopher Gassen, Raghad S. H. Saqat, Ian L. Pegg, John Philip
Summary: Thin films of ferromagnet Fe2Ge were successfully grown via molecular beam epitaxy, and their magnetic and electrical properties were measured experimentally. The material showed strong spin polarization, as indicated by the observed high-temperature maximum in the longitudinal resistivity and the suppression of electron-magnon scattering at low temperatures. Measurements of the Hall resistivity revealed contributions from both the ordinary and anomalous Hall effects, providing information about the charge carrier concentration and mobility. Additionally, small negative magnetoresistance was observed in both longitudinal and transverse geometries. Fe2Ge holds promise as a spintronic material due to its compatibility with semiconductors.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Liguo Zhang, Toni Helm, Haicheng Lin, Fengren Fan, Congcong Le, Yan Sun, Anastasios Markou, Claudia Felser
Summary: The study demonstrates that doping with vanadium can effectively modify the band structure in magnetic topological insulators, leading to the enhancement of SdH oscillations and the induction of long-range ferromagnetic order. The angle-dependent SdH oscillations reveal their 2D nature and their connection to topological surface states. This tunability by doping and the coexistence of surface states with ferromagnetism highlight the potential of Sb2-xVxTe3 thin films in energy band engineering for quantum electronics and spintronics design.
ADVANCED MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Hao Liu, Huan Zheng, Yamei Wang, Can Huang, Chunlan Ma, Yan Zhu, Hao Yang, Langsheng Ling, Lei Zhang, Jiyu Fan
Summary: In this study, a large-area CrTe film deposited on an Al2O3 substrate was analyzed. The critical exponents β=0.386(3) and γ=1.391(2) were obtained through the analysis of critical isothermal magnetization and the modified Arrott plot. Furthermore, using the renormalization group theory, it was confirmed that CrTe exhibits a quasi-2D Heisenberg-like behavior with long-range interactions. Density functional theory calculations indicated that the CrTe band structure is mainly composed of Cr atom, and the total magnetic moments are determined by the polarized spin-up t(2g) electron of Cr atom.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
Dong Li, Hongguang Wang, Kaifeng Li, Bonan Zhu, Kai Jiang, Dirk Backes, Larissa S. I. Veiga, Jueli Shi, Pinku Roy, Ming Xiao, Aiping Chen, Quanxi Jia, Tien-Lin Lee, Sarnjeet S. Dhesi, David O. Scanlon, Judith L. MacManus-Driscoll, Peter A. van Aken, Kelvin H. L. Zhang, Weiwei Li
Summary: Transition metal oxides are considered promising candidates for the next generation of spintronic devices due to their controllable properties by strain, defects, and microstructure. In this study, the authors reveal the formation of ordered oxygen vacancies and suppression of CoO6 octahedral rotations in LaCoO3 films, explaining the origin of their ferromagnetic-insulating state. The findings provide valuable insights into the mechanisms of this state and suggest potential applications in low-power spintronic devices.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Applied
Thorsten Schneider, Juliette Cardoletti, Hui Ding, Mao-Hua Zhang, Tianshu Jiang, Marton Major, Philipp Komissinskiy, Leopoldo Molina-Luna, Lambert Alff
Summary: An antipolar phase and thickness-dependent properties were confirmed for NaNbO3 thin films grown on SrTiO3 (100) substrates by pulsed laser deposition. Characteristic 1/4 superlattice reflections revealed the antipolar displacement of Na and Nb ions. X-ray diffraction showed two different orientations of the same phase for films beyond a critical thickness, with an explanation based on extraordinary strain compensation mechanism. The polarization vs electric field behavior exhibited a thickness dependence, with a stabilized antiferroelectric phase for very thin films and field induced ferroelectric hysteresis for thicker films.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Multidisciplinary
Yusong Cao, Junpeng Cao, Heng Fan
Summary: By replacing the two-level atom in the Rabi model with a ferromagnetic Heisenberg spin chain, we investigated the properties of the generalized Rabi model and found that the dynamical behavior of the system can be divided into four categories. The model is exactly solvable when magnons and photons are in resonance, and perturbation theory is used near the resonance point with small detuning. The model exhibits a spontaneously breaking of parity symmetry, indicating the presence of a quantum phase transition, with the critical exponent from the normal phase computed.
Article
Chemistry, Physical
Ting-Wei Chen, Shuang-Shuang Li, Fang Tang, Jing-Shi Ying, Ying Zhang, Zhao-Cai Wang, Shu-Juan Zhang, Fu-Sheng Luo, Lei Chen, Yong Fang, Ren-Kui Zheng
Summary: In this study, high-quality Mn2-xCrxSb (x = 0.01, 0.04, and 0.1) epitaxial thin films were grown on SrTiO3 (STO) (001) single-crystal substrates using molecular beam epitaxy. The x = 0.01 sample undergoes a quasi-ferrimagnetic (I) [Q-FIM(I)]-to-ferrimagnetic (II) [FIM(II)] spin reorientation (SR) transition and a giant magnetoresistance (MR) associated first-order ferrimagnetic(ii)-to-antiferromagnetic (AFM) phase transition upon cooling. The magnetic phase diagram of the Mn2-xCrxSb films in the low doping level region is established based on the magnetotransport and magnetic data.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Jonathan R. Chin, Marshall B. Frye, Derrick Shao-Heng Liu, Maria Hilse, Ian C. Graham, Jeffrey Shallenberger, Ke Wang, Roman Engel-Herbert, Mengyi Wang, Yun Kyung Shin, Nadire Nayir, Adri C. T. van Duin, Lauren M. Garten
Summary: Self-limiting stoichiometry promotes the growth of SnSe thin films by maintaining film stoichiometry and controlling crystallographic orientation. Results show that self-limiting stoichiometry can increase the lateral scale of SnSe layers, providing a promising avenue for device fabrication.
Article
Multidisciplinary Sciences
Alain Portavoce, Elie Assaf, Maxime Bertoglio, Dario Narducci, Sylvain Bertaina
Summary: Magnetic materials can be used to produce thermoelectric materials using spin-related effects, but a clear understanding of the interrelation between localized magnetic moments (μ(I)), free carriers, and Seebeck coefficient (S) is necessary for efficient material design. In this study, we investigate the influence of μ(I) on the spin-dependent S of model ferromagnetic thin films, allowing independent investigation of μ(I) thermal fluctuations, ordering, and density variation influence. We find that the influence of μ(I) on free carrier polarization is of utmost importance for S: efficient coupling of free carrier spin and localized magnetic moment promotes an increase in S, while spin-dependent relaxation time difference between the two spin-dependent conduction channels leads to a decrease in S. Our findings support new avenues for thermoelectric material design based on spin-related effects in ferromagnetic materials.
SCIENTIFIC REPORTS
(2023)
Article
Materials Science, Multidisciplinary
W. A. Atkinson
Summary: The study shows that electron doping destabilizes the Kittel domains in ferroelectric thin films, leading to a smooth crossover to a zigzag domain wall configuration as the electron density increases. The domain wall is positively charged but is compensated by the electron gas, potentially approaching a flat head-to-head configuration.
Article
Physics, Applied
Md Redwanul Islam, Niklas Wolff, Mohamed Yassine, Georg Schoenweger, Bjorn Christian, Hermann Kohlstedt, Oliver Ambacher, Fabian Lofink, Lorenz Kienle, Simon Fichtner
Summary: This study found that the ferroelectric-to-paraelectric transition temperature of Al1-xScxN thin film can exceed 1100 degrees C, surpassing the transition temperature of virtually any other thin film ferroelectric. Through high-temperature X-ray diffraction and permittivity measurements, it was discovered that the wurtzite-type structure of Al0.73Sc0.27N remains stable during the entire 1100 degrees C annealing cycle.
APPLIED PHYSICS LETTERS
(2021)
Article
Polymer Science
Anabella A. Abate, Cristian M. Piqueras, Daniel A. Vega
Summary: When a cylinder forming triblock copolymer thin film is exposed to supercritical carbon dioxide, it undergoes an order-order phase transition from parallel to perpendicularly oriented cylinders. Defects modify the energetic barriers for nucleation during the phase transition, with topological defects in the primitive phase surviving the transition to provide a lower bound for the density of defects in the post-transitional phase. Control over the orientational order in the primitive phase can be used to manipulate order and defects in the transversely isotropic hexagonal pattern.
Article
Materials Science, Multidisciplinary
H. J. Waring, Y. Li, C. Moutafis, I. J. Vera-Marun, T. Thomson
Summary: Researchers have found that synthetic ferromagnets have a unique layer structure, where the dynamic response of the ferromagnetic layers is closely related to the difference in magnetization and interlayer coupling. Experimental results demonstrate that conventional acoustic and optical descriptions do not fully capture the complexities of synthetic ferromagnets' dynamics.
Article
Physics, Condensed Matter
Thomas Dziuba, Ina-Marie Pietsch, Mate Stark, Georg A. Traeger, Philipp Gegenwart, Martin Wenderoth
Summary: The study reports a combined electrical transport and scanning tunneling spectroscopy (STS) investigation of the surface of sodium iridate under ultrahigh vacuum conditions. Temperature-dependent transport measurements show the presence of surface conductance with high and temperature-independent conductivity. STS reveals a variety of spectra with a significant density of states within the bandgap of sodium iridate surface. Multiple conductive channels of differing nature are simultaneously apparent in this material based on local spectroscopic information.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2021)
Review
Physics, Condensed Matter
Alexander A. Tsirlin, Philipp Gegenwart
Summary: This article reviews the progress in studying and understanding the Kitaev model on lithium iridate Li2IrO3, as well as discussing the feasibility, effectiveness, and repercussions of tuning strategies based on external pressure and chemical substitutions.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2022)
Editorial Material
Physics, Condensed Matter
Ulrich Eckern, Philipp Gegenwart
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2022)
Article
Physics, Applied
U. Arjun, K. M. Ranjith, A. Jesche, F. Hirschberger, D. D. Sarma, P. Gegenwart
Summary: Attaining millikelvin temperatures is crucial for studying quantum phenomena and operating quantum devices. Adiabatic demagnetization refrigeration (ADR) is a sustainable and effective alternative to expensive cooling methods. We present the synthesis and characterization of two UHV-compatible candidate materials, NaYbP2O7 and KYbP2O7, and report their low-temperature magnetization and specific heat measurements. Under similar conditions, the ADR of sintered pellets with Ag powder admixture achieved base temperatures of 45 mK (55 min) for NaYbP2O7 and 37 mK (35 min) for KYbP2O7, which are slightly better than KBaYb(BO3)2 (45 mK and 40 min).
PHYSICAL REVIEW APPLIED
(2023)
Article
Physics, Multidisciplinary
Rajah P. Nutakki, Richard Roess-Ohlenroth, Dirk Volkmer, Anton Jesche, Hans-Albrecht Krug von Nidda, Alexander A. Tsirlin, Philipp Gegenwart, Lode Pollet, Ludovic D. C. Jaubert
Summary: Geometric frustration prevents magnetic systems from ordering, allowing for unconventional phases of matter. Using molecular design, we have created a material [Mn(II)(ta)2] that exhibits a centered pyrochlore lattice of Mn spins, which shows features of a classical spin liquid. Despite having a Curie-Weiss temperature of -21 K, the material only orders at 430 mK, making it a highly frustrated magnet.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
A. Jesche, N. Winterhalter-Stocker, F. Hirschberger, A. Bellon, S. Bachus, Y. Tokiwa, A. A. Tsirlin, P. Gegenwart
Summary: Crystal structure, thermodynamic properties, and ADR effect of the spin-72 triangular antiferromagnet KBaGd(BO3)2 are investigated. The compound shows magnetic order below TN = 263 mK and achieves ADR temperatures as low as Tmin = 122 mK, along with improved entropy storage capacity and hold time compared to the spin-21 Yb3+ analog. The balanced interplay of exchange and dipolar couplings, combined with structural randomness and geometrical frustration, is believed to contribute to the enhanced cooling effect.
Article
Materials Science, Multidisciplinary
A. Revelli, M. Moretti Sala, G. Monaco, M. Magnaterra, J. Attig, L. Peterlini, T. Dey, A. A. Tsirlin, P. Gegenwart, T. Froehlich, M. Braden, C. Grams, J. Hemberger, P. Becker, P. H. M. van Loosdrecht, D. I. Khomskii, J. van den Brink, M. Hermanns, M. Grueninger
Summary: Ba3InIr2O9 is a promising candidate for quantum spin-liquid behavior and exhibits magnetism from spin-orbit entangled quasimolecular moments. Our study reveals its unique electronic states and excitations through various experimental and computational methods.
Article
Materials Science, Multidisciplinary
Vera P. Bader, Jan Langmann, Philipp Gegenwart, Alexander A. Tsirlin
Summary: The crystal structure and thermodynamic properties of Na2SrCo(PO4)(2), a chemical sibling of the triangular quantum spin-liquid candidate Na2BaCo(PO4)(2), have been reported. The structural difference between the two compounds leads to changes in their magnetic properties.
Article
Materials Science, Multidisciplinary
Donald M. Evans, Ola G. Grendal, L. Prodan, Maximilian Winkler, Noah Winterhalter-Stocker, Philipp Gegenwart, Somnath Ghara, Joachim Deisenhofer, Istvan Kezsmarki, V. Tsurkan
Summary: In this study, we used high-resolution synchrotron powder diffraction to investigate the evolution of the crystal structure of FeCr2S4. The results revealed a cubic to tetragonal transition at around 65K, followed by a polar transition at around 9K, resulting in a multiferroic compound. These findings provide a basis for understanding the properties of FeCr2S4 and highlight the importance of structural deformation in correlated materials.
Article
Physics, Multidisciplinary
A. Woerl, M. Garst, Y. Yamane, S. Bachus, T. Onimaru, P. Gegenwart
Summary: This study reports on the low-temperature thermal expansion and magnetostriction properties of the single-impurity quadrupolar Kondo candidate Y1-xPrxIr2Zn20. It reveals a unique temperature and magnetic field dependence, as well as a singular behavior in zero magnetic field, which is possibly induced by elastic anharmonicities or static strain disorder.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
L. Salamakha, O. Sologub, A. Riss, H. Michor, H. Mueller, B. Stoeger, G. Giester, P. Rogl, A. Sakai, P. Gegenwart, E. Bauer
Summary: Novel ternary platinum borides YbPt5B2 and LuPt5B2 were synthesized and their crystal structures and electronic properties were investigated. YbPt5B2 exhibits heavy fermion behavior, while LuPt5B2 shows typical metallic behavior.
Article
Materials Science, Multidisciplinary
M. Majumder, R. Gupta, H. Luetkens, R. Khasanov, O. Stockert, P. Gegenwart, V. Fritsch
Summary: CePdAl is a frustrated Kondo lattice with partial long-range order. Under pressure, the long-range order is completely suppressed, and spin-liquid behavior is observed. There is a quantum critical regime between pressure and temperature.
Article
Materials Science, Multidisciplinary
Bin Shen, Franziska Breitner, Danil Prishchenko, Rudra Sekhar Manna, Anton Jesche, Maximilian L. Seidler, Philipp Gegenwart, Alexander A. Tsirlin
Summary: Magnetization measurements were performed on α-Li2IrO3 under hydrostatic pressures, and the temperature-pressure phase diagram was established. The material undergoes a first-order phase transition from a magnetic phase to a nonmagnetic dimerized phase above 1.2 GPa. The critical pressure of the structural dimerization shows strong temperature dependence.
Article
Materials Science, Multidisciplinary
Bin Shen, Anton Jesche, Maximilian L. Seidler, Friedrich Freund, Philipp Gegenwart, Alexander A. Tsirlin
Summary: The study investigates the magnetic behavior and dimerization features of β-Li2IrO3 under high pressures, confirming a first-order phase transition of magnetic order at 1.4 GPa. Based on first-principles calculations, a partially dimerized phase is found to be thermodynamically stable between 1.7 and 2.7 GPa.
Article
Materials Science, Multidisciplinary
Jiongyao Wu, Marcel Zoellner, Sebastian Esser, Vijaya Begum, Guenther Prinz, Axel Lorke, Philipp Gegenwart, Rossitza Pentcheva
Summary: The electronic, magnetic, and optical properties of the double perovskite Sr2CoIrO6 under biaxial strain were investigated using density functional theory with Hubbard U term and spin-orbit coupling, revealing that Co and Ir exhibit different spin and orbital moments under varying strain conditions. The band gap shows a nonmonotonic change due to the inclusion of many-body effects, including excitonic effects. The study highlights the complex electronic structure and optical properties of SCIO.
