Article
Multidisciplinary Sciences
Senad Bulja, Rose Kopf, Al Tate, Mark Cappuzzo, Dmitry Kozlov, Holger Claussen, Dirk Wiegner, Wolfgang Templ, Dariush Mirshekar-Syahkal
Summary: Resistive switching (RS) of Transition Metal Oxides (TMOs) is a promising option for the development of next generation memory and 6G wireless communication technologies. The exact mechanism of RS is not yet fully understood, but it is believed to involve the formation and rupture of conductive filaments in the oxide materials. The study reveals the differences in switching behavior and resistance between amorphous TiO2 and NiO, with TiO2 showing superior high frequency characteristics. These findings are important for understanding the conduction mechanism in binary/multinary oxides and enabling their use in non-volatile memory and 6G applications.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Multidisciplinary
M. Okawa, D. Takegami, D. S. Christovam, M. Ferreira-Carvalho, C. -Y. Kuo, C. T. Chen, T. Miyoshino, K. Takasu, T. Okuda, C. F. Chang, L. H. Tjeng, T. Mizokawa
Summary: The research investigates the differences in the titanium 3d orbitals between corundum-type Ti2O3 and ilmenite-type MgTiO3 using linear dichroism of soft x-ray absorption spectroscopy. The study confirms the presence of the Ti-Ti bond and the change in symmetry of the 3d orbitals under hole doping.
Article
Materials Science, Multidisciplinary
Yunqi Cao, Tongyu Wang, Nelson Sepulveda
Summary: A microfluidic thermal mass flow sensor using planar micro-machining technology and a phase-change material has been developed. By utilizing vanadium dioxide (VO2) thin film, no thermal insulation structure is needed due to the high thermal sensitivity in the phase transition region. The sensor exhibits a 3-order resistance change during heating and cooling cycles, with a maximum sensitivity of 1.383%/(mu L min(-1)). The research suggests the potential application of nonlinear metamaterials for highly sensitive microfluidic flow sensors.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Physics, Applied
G. M. Hunt, J. A. Miragliotta, J. Ginn, A. P. Warren, D. B. Shrekenhamer
Summary: This article introduces a passive and adaptive thermal management system that utilizes the properties of VO2 material to provide insulation at low temperatures and heat dissipation at high temperatures, thereby reducing energy consumption. By doping VO2 with high valence tungsten, the transition temperature can be close to room temperature. By carefully engineering the thickness and doping of the VO2 layer in the multilayer film, a 50% emissive contrast was maintained across the 8-13 μm spectral region.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Qiao Jin, Hu Cheng, Zhiwen Wang, Qinghua Zhang, Shan Lin, Manuel A. Roldan, Jiali Zhao, Jia-Ou Wang, Shuang Chen, Meng He, Chen Ge, Can Wang, Hui-Bin Lu, Haizhong Guo, Lin Gu, Xin Tong, Tao Zhu, Shanmin Wang, Hongxin Yang, Kui-juan Jin, Er-Jia Guo
Summary: The study reveals that by controlling the film thickness of highly crystalline CrN films, a significant reduction in electrical conductivity accompanied by unexpected volume expansion can be observed. When the film thickness reaches approximately 30 unit cells, the conductivity of CrN films is greatly reduced.
ADVANCED MATERIALS
(2021)
Article
Multidisciplinary Sciences
Yekai Song, Chunjing Jia, Hongyu Xiong, Binbin Wang, Zhicheng Jiang, Kui Huang, Jinwoong Hwang, Zhuojun Li, Choongyu Hwang, Zhongkai Liu, Dawei Shen, Jonathan A. Sobota, Patrick Kirchmann, Jiamin Xue, Thomas P. Devereaux, Sung-Kwan Mo, Zhi-Xun Shen, Shujie Tang
Summary: The authors report electronic properties of monolayer ZrTe2 from ARPES and STM measurements that are consistent with the preformed exciton gas phase, a precursor for the excitonic insulator.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Chen Li, Ke Liu, Dequan Jiang, Huacai Yan, En Chen, Yingying Ma, Haoming Cheng, Ting Wen, Binbin Yue, Yonggang Wang
Summary: This study demonstrates the pressure-induced multi-transition of both structure and physical properties in violet phosphorus, a novel phosphorus allotrope. Violet phosphorus exhibits emergent insulator-metal transition, superconductivity, and dramatic switching from positive to negative photoconductivity under compression. The resistance of violet phosphorus shows a sudden drop, and piezochromism and suppression of photoluminescence are observed upon compression. The sample irreversibly transforms into black phosphorus with different physical properties after decompression.
Article
Physics, Multidisciplinary
Arvind Shankar Kumar, Chieh-Wen Liu, Shuhao Liu, Xuan P. A. Gao, Alex Levchenko, Loren N. Pfeiffer, Kenneth W. West
Summary: We report an unusual magnetoresistance in a dilute two-dimensional hole system in GaAs/AlGaAs quantum wells, where the magnetoresistance strengthens with increasing temperature even at the Fermi energy. This positive magnetoresistance at high temperatures is attributed to the viscous transport of the 2D hole fluid in the hydrodynamic regime. These findings provide insights into the collective transport of strongly interacting carriers and offer new possibilities for high-temperature magnetoresistance.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Aditya Sood, Xiaozhe Shen, Yin Shi, Suhas Kumar, Su Ji Park, Marc Zajac, Yifei Sun, Long-Qing Chen, Shriram Ramanathan, Xijie Wang, William C. Chueh, Aaron M. Lindenberg
Summary: Understanding the pathways and time scales underlying electrically driven insulator-metal transitions is vital for uncovering the fundamental limits of device operation. By using stroboscopic electron diffraction, researchers discovered an electrically triggered, isostructural state that forms transiently on microsecond time scales and established electrical excitation as a route for uncovering nonequilibrium and metastable phases in correlated materials. This metastable phase is similar to that formed under photoexcitation within picoseconds, suggesting a universal transformation pathway.
Article
Chemistry, Physical
Wenqiang Xiang, Boris Le Drogoff, Mohamed Chaker
Summary: Depositing high-quality VO2 thin films on a large area has been a challenge. This study presents an improved technique called sputtering oxidation coupling (SOC) using VN as intermediate material. VN films are first deposited on quartz by magnetron sputtering and then annealed in oxygen to obtain VO2 films with good performance in terms of transition properties. The proposed method is comparable to Pulsed Laser Deposition (PLD) in producing high-quality VO2 films.
APPLIED SURFACE SCIENCE
(2023)
Article
Crystallography
Xiaoli Wang, Shilei Wang, Chao Liu, Chuanyan Fan, Lu Han, Feiyu Li, Tieyan Chang, Yu-Sheng Chen, Shanpeng Wang, Xutang Tao, Junjie Zhang
Summary: Single crystals of the perovskite nickelate NdNiO3 have been grown using the flux method at a temperature of 400 degrees C and oxygen pressure of 200 bar. The crystals were characterized using various techniques and showed a metal-insulator transition at around 180 K. The successful growth of these crystals at relatively low temperatures and oxygen pressure provides an alternative approach for preparing other perovskite materials.
Article
Materials Science, Multidisciplinary
Yujie Wang, Chenchen Lou, Bao Zhao, Chunlan Ma, Jiayong Zhang
Summary: In this study, the electronic, magnetic, and topological properties of monolayer NiAl2S4 were investigated using first-principles calculations. Monolayer NiAl2S4 was found to be in a noncollinear 1200-antiferromagnetic state and have an indirect band gap, making it a promising candidate for spintronics devices. Hole doping can effectively tune the magnetic structure of monolayer NiAl2S4, resulting in a high Curie temperature half-metallic state. Additionally, the inclusion of spin-orbit coupling leads to the opening of topologically nontrivial gaps with Chern numbers of 1 around the non-Dirac I' point and Dirac K/K' points.
Article
Physics, Multidisciplinary
C. L. Tschirhart, Evgeny Redekop, Lizhong Li, Tingxin Li, Shengwei Jiang, T. Arp, O. Sheekey, Takashi Taniguchi, Kenji Watanabe, M. E. Huber, Kin Fai Mak, Jie Shan, A. F. Young
Summary: Magnetic switching via spin-orbit torque is demonstrated in a moire bilayer, providing a platform for spintronic applications.
Article
Physics, Applied
Raju B. Naik, Divya Verma, Viswanath Balakrishnan
Summary: This work investigates the variation in threshold voltage of memristor behavior in tungsten-doped VO2 crystals. The effects of chemical doping on the metal-insulator transition are studied through Raman spectroscopy and differential scanning calorimetry. Additionally, the bi-polar threshold switching of VO2 memristor behavior is demonstrated in microcrystals with different contents of tungsten.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Paul C. Lou, Anand Katailiha, Ravindra G. Bhardwaj, W. P. Beyermann, Dheeraj Mohata, Sandeep Kumar
Summary: In the metal/degenerately doped silicon bilayer structure, the interfacial flexoelectric effect leads to charge carrier transfer from metal layer to the silicon layer, resulting in an electronically polarized silicon layer with magnetism. By controlling the flexoelectronic doping, material behavior can be engineered for quantum, spintronics, and electronics applications in semiconductor materials.
Article
Chemistry, Multidisciplinary
E. Georgopoulou-Kotsaki, P. Pappas, A. Lintzeris, P. Tsipas, S. Fragkos, A. Markou, C. Felser, E. Longo, M. Fanciulli, R. Mantovan, F. Mahfouzi, N. Kioussis, A. Dimoulas
Summary: The 2D van der Waals ferromagnetic metals FexGeTe2 with x = 3-5 have attracted significant attention. In this study, epitaxial Fe5-dGeTe2 (FGT) heterostructures were grown on insulating crystalline substrates using Molecular Beam Epitaxy (MBE). The addition of Bi2Te3 topological insulator (TI) to FGT films significantly enhanced the saturation magnetization and Curie temperature (Tc), with record values of 570 K obtained.
Article
Physics, Multidisciplinary
Daniel S. S. Sanchez, Tyler A. A. Cochran, Ilya Belopolski, Zi-Jia Cheng, Xian P. Yang, Yiyuan Liu, Tao Hou, Xitong Xu, Kaustuv Manna, Chandra Shekhar, Jia-Xin Yin, Horst Borrmann, Alla Chikina, Jonathan D. D. Denlinger, Vladimir N. N. Strocov, Weiwei Xie, Claudia Felser, Shuang Jia, Guoqing Chang, M. Zahid Hasan
Summary: The classification of electronic phases is based on two prominent paradigms: correlations and topology. Electron correlations lead to superconductivity and charge density waves, while the Berry phase gives rise to electronic topology. The combination of these two paradigms has prompted the search for electronic instabilities near the Fermi level of topological materials. This study identifies the electronic topology of chiral fermions as the driving force behind van Hove singularities that host electronic instabilities in the surface band structure.
Article
Physics, Multidisciplinary
Norbert H. H. Freitag, Christopher F. F. Reiche, Volker Neu, Parul Devi, Ulrich Burkhardt, Claudia Felser, Daniel Wolf, Axel Lubk, Bernd Buechner, Thomas Muehl
Summary: This article presents a quantitative magnetic force microscopy technique that can simultaneously map one magnetic stray-field component and its spatial derivative. It is applied to investigate circular magnetic nano-domains in MnNiGa bulk samples, providing bubble diameters and spatial extent in depth. The experimental results indicate that the magnetic bubbles have a significant spatial extent in depth and a buried bubble top base.
COMMUNICATIONS PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Hyeuk Jin Han, Sushant Kumar, Gangtae Jin, Xiaoyang Ji, James L. Hart, David J. Hynek, Quynh P. Sam, Vicky Hasse, Claudia Felser, David G. Cahill, Ravishankar Sundararaman, Judy J. Cha
Summary: The increasing resistance of copper (Cu) interconnects in integrated circuits is a major challenge for downscaling beyond 7 nm technology. Topological semimetals like molybdenum phosphide (MoP) nanowires show unprecedented resistivity scaling, superior to nanoscale Cu interconnects. MoP has better stability against electromigration and resistance to surface oxidation compared to Cu, making it an attractive alternative for the scaling challenge of Cu interconnects.
ADVANCED MATERIALS
(2023)
Correction
Multidisciplinary Sciences
Yudi Zhang, Kathryn E. Arpino, Qun Yang, Naoki Kikugawa, Dmitry A. Sokolov, Clifford W. Hicks, Jian Liu, Claudia Felser, Guowei Li
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Subhajit Roychowdhury, Mengyu Yao, Kartik Samanta, Seokjin Bae, Dong Chen, Sailong Ju, Arjun Raghavan, Nitesh Kumar, Procopios Constantinou, Satya N. Guin, Nicholas Clark Plumb, Marisa Romanelli, Horst Borrmann, Maia G. Vergniory, Vladimir N. Strocov, Vidya Madhavan, Chandra Shekhar, Claudia Felser
Summary: In this study, the electronic structure of ferromagnetic EuCd2As2, predicted to be an ideal Weyl semimetal, is investigated using angle-resolved photoemission spectroscopy and scanning tunneling microscopy. The experimental results are in close agreement with the first principles calculations. Furthermore, anomalous Hall conductivity and Nernst effect are observed, resulting from the non-zero Berry curvature and the topological Hall effect arising from changes in the band structure caused by spin canting produced by magnetic fields. These findings provide insights into exotic quantum phenomena in inorganic topological materials with multiple pairs of Weyl nodes.
Article
Materials Science, Multidisciplinary
Hua Lv, Edouard Lesne, Rebeca Ibarra, Yan Sun, Anastasios Markou, Claudia Felser
Summary: In this study, the structural, magnetic, and electrical magnetotransport properties of 24 and 51 nm thick B20-RhSi thin films grown by magnetron sputtering were investigated. The films exhibited a nonmagnetic ground state and metallic behavior. It was confirmed that the temperature-dependent electrical resistivity is governed by electron-phonon scattering. The ability to grow textured-epitaxial thin films of nonmagnetic B20 chiral topological semimetals is an important step toward designing chiraltronic devices with novel functionalities.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Luca Tomarchio, Sen Mou, Lorenzo Mosesso, Anastasios Markou, Edouard Lesne, Claudia Felser, Stefano Lupi
Summary: In this paper, we investigate the terahertz emission from thin films of the magnetic topological nodal semimetal Co2MnGa when excited by femtosecond optical pulses. We identify multiple THz generation mechanisms, including a photon-drag effect induced by radiation pressure and a photovoltaic effect from the topological surface states of CMG. This interplay between generation mechanisms highlights the potential of Co2MnGa topological nodal semimetals for THz emitter devices.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Andrew M. Ochs, Gerhard H. Fecher, Bin He, Walter Schnelle, Claudia Felser, Joseph P. Heremans, Joshua E. Goldberger
Summary: KMgBi is a quantum material that exhibits axis-dependent conduction polarity and a greatly enhanced ordinary Nernst effect (ONE). It shows a significant zero-field transverse thermoelectric response and a new type of Nernst effect.
ADVANCED MATERIALS
(2023)
Review
Nanoscience & Nanotechnology
Georgios Varnavides, Amir Yacoby, Claudia Felser, Prineha Narang
Summary: As high-quality single-crystal materials used in electronic devices reach smaller scales, charge-transport phenomena lead to inhomogeneous spatial signatures with significant effects on material properties. These signatures, including spatially varying dissipation and interface resistance, are crucial for device control. This Review examines the inhomogeneous charge flow signatures in conductors, focusing on electron hydrodynamics, where electrons exhibit strong interactions and flow collectively like fluids. Recent experimental advances and theoretical frameworks are discussed, along with new charge-transport phenomena introduced by crystal symmetry in materials.
NATURE REVIEWS MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Irian Sanchez-Ramirez, Maia G. Vergniory, Claudia Felser, Fernando de Juan
Summary: Among the quasi-one-dimensional transition metal tetrachalcogenides (MSe4)nI (M = Nb,Ta), the n = 3 compounds exhibit structural transitions with puzzling transport behavior instead of charge density waves. Recent discovery of a metallic polytype of (TaSe4)3I with coexisting ferromagnetism and superconductivity at low temperature challenges previous reports. In this study, ab initio and tight-binding band-structure calculations are used to explain the observed transport gaps and clarify the controversy regarding ARPES and optical conductivity experiments. The effect of small extrinsic hole doping and its implications for magnetism and superconductivity are also discussed.
Article
Materials Science, Multidisciplinary
M. O. Ajeesh, P. Materne, R. D. dos Reis, K. Weber, S. Dengre, R. Sarkar, R. Khasanov, I. Kraft, A. M. Leon, W. Bi, J. Zhao, E. E. Alp, S. Medvedev, V. Ksenofontov, H. Rosner, H. -H. Klauss, C. Geibel, M. Nicklas
Summary: LuFe4Ge2 crystallizes in a structure with chains of Fe tetrahedra, leading to geometric frustration and low dimensionality. The compound exhibits antiferromagnetic ordering at around 36 K, accompanied by a structural transition. The dependence of these transitions on hydrostatic pressure is investigated, revealing a suppression of the antiferromagnetic phase and the appearance of a new antiferromagnetic phase at higher pressures.
Article
Materials Science, Multidisciplinary
Lun-Hui Hu, Chunyu Guo, Yan Sun, Claudia Felser, Luis Elcoro, Philip J. W. Moll, Chao-Xing Liu, Andrei Bernevig
Summary: In this study, a hierarchical structure of quasisymmetries and their corresponding nodal structures in the chiral crystal material CoSi are revealed through two different approaches of perturbation expansions. Quasisymmetries are found to play a crucial role in the physical responses of the system and can protect the existence of nodal planes.
Article
Materials Science, Multidisciplinary
Eleanor F. Scott, Katherine A. Schlaak, Poulomi Chakraborty, Chenguang Fu, Satya N. Guin, Safa Khodabakhsh, Ashley E. Paz Y. Puente, Claudia Felser, Brian Skinner, Sarah J. Watzman
Summary: In this study, it was discovered that polycrystalline NbP exhibits a large Nernst effect and a large magneto-Seebeck effect simultaneously, which is rarely observed in a single material at the same temperature. Through doping, the temperature dependence of these magnetothermoelectric effects can be altered, providing a potential tuning mechanism for device applications.
Article
Engineering, Electrical & Electronic
Ryotaro Okabe, Mingda Li, Yuma Iwasaki, Nicolas Regnault, Claudia Felser, Masafumi Shirai, Alexander Kovacs, Thomas Schrefl, Atsufumi Hirohata
Summary: This letter summarizes the recent development of using artificial intelligence and machine learning in the search for magnetic materials, and briefly introduces the approaches used in materials discovery. The authors also provide a flowchart to assist in selecting the appropriate methods for material search. The letter also covers the authors' recent research activities in magnetism and quantum materials.
IEEE MAGNETICS LETTERS
(2023)