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
Physics, Multidisciplinary
Zhiting Gao, Minghua Guo, Zichen Lian, Yaoxin Li, Yunhe Bai, Xiao Feng, Ke He, Yayu Wang, Chang Liu, Jinsong Zhang
Summary: We have developed a low-damage photolithography method for fabricating magnetically doped (Bi,Sb)(2)Te-3 quantum anomalous Hall (QAH) thin film devices. Through experiments, we demonstrated that this modified method enables the production of devices with unaffected transport and magnetic properties.
Article
Chemistry, Physical
Ming Tan, Xiao-Lei Shi, Wei-Di Liu, Meng Li, Yaling Wang, Hui Li, Yuan Deng, Zhi-Gang Chen
Summary: By carefully tuning the deposition temperature to enhance the texture and induce Bi/Sb-Te antisite doping in Bi0.5Sb1.5Te3 thin films, a high ZT value of approximately 1.5 was achieved, showing great potential for practical applications.
ADVANCED ENERGY MATERIALS
(2021)
Article
Chemistry, Physical
Yuyou Zhang, Kaikai Pang, Qiang Zhang, Yanan Li, Wenjie Zhou, Xiaojian Tan, Jacques G. Noudem, Gang Wu, Lidong Chen, Haoyang Hu, Peng Sun, Jiehua Wu, Guo-Qiang Liu, Jun Jiang
Summary: This study successfully enhances the thermoelectric performance of Bi2Te3-based alloys by subtly incorporating non-stoichiometric Ag5Te3 and counteractive Se. The addition of Ag5Te3 and Se improves the electrical transport properties and lowers the lattice thermal conductivity. When coupled with other thermoelectric materials, the integrated TE module exhibits significantly improved conversion efficiency and power density, demonstrating great potential for practical applications.
Article
Chemistry, Physical
Guojuan Qiu, Juan Li, Yifeng Ling, Guoying Dong, Jianghe Feng, Ping Zhang, Ruiheng Liu
Summary: By controlling the Te target co-sputtering power, annealing temperature and time, the carrier concentration and orientation of (Sb,Bi)2Te3 films are optimized in this work, resulting in high power factors. In addition, the thermal conductivity along in-plane direction is determined by TPET technique, and the zT values for Sb2Te3 and Bi0.5Sb1.5Te3 films are obtained.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Engineering, Environmental
Deyu Bao, Qiang Sun, Linsen Huang, Jie Chen, Jun Tang, Dali Zhou, Min Hong, Lei Yang, Zhi-Gang Chen
Summary: Efforts have been made to improve p-type (Bi, Sb)(2)Te-3-based thermoelectric materials for commercial applications. By utilizing surface decoration and doping methods, the thermal conductivity has been decreased and the Seebeck coefficient has been increased, leading to enhanced overall performance of the thermoelectric materials.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Hua-Lu Zhuang, Haihua Hu, Jun Pei, Bin Su, Jing-Wei Li, Yilin Jiang, Zhanran Han, Jing-Feng Li
Summary: This study successfully improved the thermoelectric performance of (Bi,Sb)2Te3-based alloys by incorporating BiI3 and Zn as dopants. BiI3 introduced nanoscale pores that reduced thermal conductivity, while Zn improved electrical conductivity and prevented deterioration. The modulation of thermal and electrical transport properties significantly improved the ZT value.
ENERGY & ENVIRONMENTAL SCIENCE
(2022)
Article
Chemistry, Inorganic & Nuclear
Lidia N. Lukyanova, Yuri A. Boikov, Oleg A. Usov, Viacheslav A. Danilov, Igor V. Makarenko, Vasilii N. Petrov
Summary: In this study, the temperature dependencies of the total, crystal lattice, and electronic thermal conductivities in films of topological insulators were investigated. It was found that the lattice thermal conductivity decreased due to the scattering of long-wavelength phonons on the grain interfaces. The energy dependence of the relaxation time in films with low thermal conductivity was enhanced, which is specific to topological insulators. The thermal conductivity was correlated with the morphology of the interlayer surface (0001) in the studied films.
Article
Chemistry, Multidisciplinary
Alexander S. Frolov, Dmitry Yu. Usachov, Alexander V. Fedorov, Oleg Yu. Vilkov, Vladimir Golyashov, Oleg E. Tereshchenko, Artem S. Bogomyakov, Konstantin Kokh, Matthias Muntwiler, Matteo Amati, Luca Gregoratti, Anna P. Sirotina, Artem M. Abakumov, Jaime Sanchez-Barriga, Lada Yashina
Summary: In this study, the atomic structure and electronic/magnetic properties of Mn0.06Sb1.22Bi0.78Te3.06 material were revealed. The material naturally forms ferromagnetic layers inside an insulating matrix, with tunable Fermi level and topologically nontrivial surface states. Different terminations were observed on cleaved surfaces, and manganese atoms were found to preferentially occupy the central positions in septuple layers.
Article
Materials Science, Multidisciplinary
Fariba Moshtaghi, Mardali Yousefpour, Ali Habibolahzadeh
Summary: Polyaniline-Bi-Sb-Te-Se thin films were fabricated on aluminum substrate using electrodeposition and electrochemical reaction method. The structure and morphology of the films were analyzed by FTIR, XRD, FE-SEM, and EDS. The electrical and thermoelectric properties of the films were evaluated, and it was found that the chemical composition and applied potential greatly influenced the thermoelectric properties. Furthermore, a slight change in the chemical compound improved the thermoelectric properties by approximately 65%.
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS
(2023)
Article
Materials Science, Ceramics
Hao Zhao, Baoyin Xu, Zhanhui Ding, Yanfeng Xue, Jing Yang, Wei Zhao, Yongfeng Li, Bin Yao, Hongdong Li, Yucheng Lan
Summary: By fabricating porous structures, the thermal conductivity of Bismuth telluride was reduced, leading to improved thermoelectric properties. The study showed that porous (Bi,Sb)2Te3 materials with increased porosity and pore size had significantly lower thermal conductivity. This method of preparing porous thermoelectric materials has potential for enhancing thermoelectric performances.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
N. P. Stepina, A. O. Bazhenov, A. V. Shumilin, A. Yu. Kuntsevich, V. V. Kirienko, E. S. Zhdanov, D. V. Ishchenko, O. E. Tereshchenko
Summary: In this study, magneto-resistance measurements were conducted in (Bi, Sb)2(Te, Se)3 3D topological insulator thin films grown on Si(111) substrate, revealing anomalous weak antilocalization effects and non-linear weak magnetic field Hall effect. A two-liquid model was used to explain both transport features, suggesting a possible correlation with the Zeeman-field-induced gap opening mechanism.
Article
Materials Science, Ceramics
Marek Bouska, Virginie Nazabal, Jan Gutwirth, Tomas Halenkovic, Petr Nemec
Summary: Radio-frequency magnetron co-sputtering technique was employed to deposit Ge-Sb-Te amorphous thin films, covering a broad range of chemical composition. Large variations in electrical and optical contrast were observed upon annealing-induced crystallization, with the importance of GeTe content in Ge-Sb-Te thin films confirmed.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2021)
Article
Materials Science, Multidisciplinary
Jun Pei, Jinfeng Dong, Bowen Cai, Yuan Zhang, Wei Zhou, Bo-Ping Zhang, Zhen-Hua Ge, Jing-Feng Li
Summary: This study investigated the doping effect of Fe on Bi-Sb-Te based materials and introduced weak-ferromagnetism to enhance the thermoelectric performance at room temperature. The maximum power factor and ZT value reached 45 mWcm(-1)K(-2) and 1.2, respectively, demonstrating the effectiveness of this approach in improving TE properties.
MATERIALS TODAY PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Yan-Lin Wang, Tsung-Han Chen, Karan Giri, Chun-Hua Chen
Summary: This study successfully demonstrated the application of longitudinally periodic DLC layers in BST-based nanostructures, which effectively improves the Seebeck coefficient and power factor while reducing thermal transport.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Run Xiao, Jacob T. Held, Jeffrey Rable, Supriya Ghosh, Ke Wang, K. Andre Mkhoyan, Nitin Samarth
Summary: Magnetic doping of topological quantum materials provides an attractive method for studying the effects of time reversal symmetry breaking. The introduction of transition metal Mn into Cd3As2 films shows the formation of a Mn-rich phase at the top surface, indicating that Mn acts as a surfactant during epitaxial growth of Cd3As2.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Multidisciplinary
Lauren J. Riddiford, Alexander J. Grutter, Timothy Pillsbury, Max Stanley, Danielle Reifsnyder Hickey, Peng Li, Nasim Alem, Nitin Samarth, Yuri Suzuki
Summary: We have studied magnetic insulator-topological insulator heterostructures and identified a possible magnetic proximity effect in MgAl0.5Fe1.5O4/Bi2Se3 bilayers. Electrical transport and polarized neutron reflectometry confirm the existence of a magnetic proximity effect, while structural data reveal the disordered interface as the origin of the magnetic response.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Pengxiang Zhang, Chung-Tao Chou, Hwanhui Yun, Brooke C. McGoldrick, Justin T. Hou, K. Andre Mkhoyan, Luqiao Liu
Summary: Injecting spin currents into antiferromagnets can rotate and switch the Néel vector within the tilted easy plane, comparable to classical ferrimagnetic insulators. This study introduces a new platform for quantitatively characterizing switching and oscillation dynamics in antiferromagnets.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Ke Huang, Hailong Fu, Danielle Reifsnyder Hickey, Nasim Alem, Xi Lin, Kenji Watanabe, Takashi Taniguchi, Jun Zhu
Summary: In this study, we investigate the control over valley isospin degrees of freedom in bilayer graphene using a perpendicular electric field. We observe a new even-denominator fractional quantum Hall state at filling factor v = 5/2 and the appearance of predicted daughter states and anti-Pfaffian states. These findings pave the way for manipulating valley isospin in bilayer graphene to engineer exotic topological orders and quantum information processes.
Article
Physics, Applied
Yihong Fan, Zach Cresswell, Silu Guo, Delin Zhang, Thomas J. Peterson, Jinming Liu, Yang Lv, K. Andre Mkhoyan, Jian-Ping Wang
Summary: In this study, a large USMR value was observed in sputtered amorphous PtSn4/CoFeB bilayers, which is 50% larger than reported values from heavy metals. This finding provides an alternative pathway for USMR application in two-terminal SOT devices.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Deyuan Lyu, Pravin Khanal, Yang Lv, Bowei Zhou, Hwanhui Yun, Qi Jia, Brandon R. Zink, Yihong Fan, K. Andre Mkhoyan, Weigang Wang, Jian-Ping Wang
Summary: This study investigates Mo-based perpendicular magnetic tunnel junctions (Mo-pMTJs), which exhibit superior perpendicular magnetic anisotropy (PMA) and thermal tolerance compared to mainstream Ta-pMTJs. The ultrafast switching behavior of Mo-pMTJ devices is explored, with a focus on the precessional regime at sub-ns timescales. The optimization of switching energy is discussed. Furthermore, the magneto-transport properties and switching behavior of Mo-pMTJs at low temperatures down to 2 K are investigated, demonstrating the feasibility of utilizing Mo-pMTJ devices in cryogenic memory applications.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Run Xiao, Saurav Islam, Wilson Yanez, Yongxi Ou, Haiwen Liu, Xincheng Xie, Juan Chamorro, Tyrel M. McQueen, Nitin Samarth
Summary: Time-reversal invariance and inversion symmetry are responsible for the topological band structure in Dirac semimetals. Applying an external magnetic or electric field can break these symmetries and cause fundamental changes to the ground state Hamiltonian and a topological phase transition. We use universal conductance fluctuations in Cd3As2 to probe these changes. The magnitude of the fluctuations decreases with increasing magnetic field, consistent with the effect of broken time-reversal invariance. However, the magnitude increases monotonically when the chemical potential is gated away from the charge neutrality point, attributed to Fermi surface anisotropy rather than broken inversion symmetry. The agreement between experimental data and theory provides unequivocal evidence that universal conductance fluctuations are the dominant source of fluctuations and offers a general methodology for probing broken-symmetry effects in topological quantum materials.
Article
Chemistry, Multidisciplinary
Saiphaneendra Bachu, Malgorzata Kowalik, Benjamin Huet, Nadire Nayir, Swarit Dwivedi, Danielle Reifsnyder Hickey, Chenhao Qian, David W. Snyder, Slava V. Rotkin, Joan M. Redwing, Adri C. T. van Duin, Nasim Alem
Summary: By combining experiments and theory, we investigated the influence of stacking order and twist angle of CVD graphene on the nucleation of WSe2 crystals. We found that interlayer dislocations are present only in Bernal-stacked bilayer graphene, not in twisted bilayer graphene. The localized buckles in Bernal-stacked graphene serve as thermodynamically favorable sites for binding WSe x molecules, resulting in a higher nucleation density of WSe2.
Article
Physics, Applied
Chi Zhang, Fengdeng Liu, Silu Guo, Yingying Zhang, Xiaotian Xu, K. Andre Mkhoyan, Bharat Jalan, Xiaojia Wang
Summary: As an ultrawide bandgap semiconductor, single crystalline SrSnO3 (SSO) shows potential for power electronics and transparent conductor applications, but its device performance can be limited by heat dissipation issues. This study investigates the temperature-dependent thermal properties of a single crystalline SSO thin film and provides physical insights into its thermal transport mechanisms. The results reveal that the thermal conductivity of the SSO film is lower than other perovskite oxides at room temperature, attributed to its unique distorted orthorhombic structure. At high temperatures, the thermal conductivity of SSO decreases with temperature following a weaker dependence than typical trends dominated by Umklapp scattering. This work not only improves our understanding of thermal transport in single crystalline SSO but also has implications for the thermal design and optimization of SSO-based electronic applications.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Hwanhui Yun, Delin Zhang, Turan Birol, Jian-Ping Wang, K. Andre Mkhoyan
Summary: Using atomic-resolution scanning transmission electron microscopy, this study captures atomic movements and rearrangements in the Pt-Sn system during solid-solid phase transformations, providing details of the underlying mechanisms. The PtSn4 to PtSn2 transformation is preceded by a periodic superlattice substructure and an intermediate structure templated by the anisotropic crystal structure of the parent phase. The PtSn(2) to Pt2Sn3 transformation is dictated by the anisotropy of the product Pt2Sn3 structure. Analysis of atomic configurations at the transformation front reveals the diffusion pathways and lattice distortions involved. Comparison of multiple transformations in the Pt-Sn system elucidates the structural parameters governing solid-solid phase transformations in this intermetallic system.
Article
Materials Science, Multidisciplinary
Fan Zhang, Asmaul Smitha Rashid, Mostafa Tanhayi Ahari, Wei Zhang, Krishnan Mekkanamkulam Ananthanarayanan, Run Xiao, George J. de Coster, Matthew J. Gilbert, Nitin Samarth, Morteza Kayyalha
Summary: There is a growing interest in using multiterminal Josephson junctions to emulate topological phases and investigate superconducting mechanisms. However, the interpretation of experimental signatures in MTJJs has been conflicting. In this study, graphene-based four-terminal Josephson junctions were investigated experimentally and theoretically. Resonant features in the differential resistance maps were observed and successfully reproduced using a circuit network model. The study suggests that differential resistance measurements alone cannot distinguish resonant Andreev reflection processes from semiclassical circuit-network effects.
Article
Optics
Chengyun Hong, Saejin Oh, Vu Khac Dat, Sangyeon Pak, SeungNam Cha, Kyung-Hun Ko, Gyung-Min Choi, Tony Low, Sang-Hyun Oh, Ji-Hee Kim
Summary: Transition metal dichalcogenide (TMD) layered semiconductors have immense potential in various device applications. However, their sub-bandgap light absorption is insufficient. In this study, we modulated the sub-bandgap photoresponse of MoS2/Au heterostructures through electrode fabrication methods. By applying a sputter deposition of the Au layer, we achieved up to 60% sub-bandgap absorption in the MoS2/Au heterostructure. The enhanced absorption was attributed to the planar cavity formed by MoS2 and Au, and the absorption spectrum could be tuned by altering the thickness of the MoS2 layer. The SWIR photocurrent increased due to increased absorption, enabling broad wavelength detection. Rapid photoresponse and high responsivity were achieved at an excitation wavelength of 1550 nm. This study demonstrates a facile method for optical property modulation and SWIR photodetection in wide-bandgap 2D materials.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Juhan Kim, Hwanhui Yun, Jihoon Seo, Jae Ha Kim, Jae Hoon Kim, K. Andre Mkhoyan, Bongju Kim, Kookrin Char
Summary: This study investigates the electrical, structural, and optical properties of La-doped SrSnO3 thin films with varying thickness. It is found that with increasing film thickness, vertical grain boundaries are formed and the orthorhombic phase is reoriented. The analysis of optical transmittance shows that La-doped SrSnO3 thin films have a high figure of merit in the deep-UV region.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Tzia Ming Onn, Sallye R. Gathmann, Yuxin Wang, Roshan Patel, Silu Guo, Han Chen, Jimmy K. Soeherman, Phillip Christopher, Geoffrey Rojas, K. Andre Mkhoyan, Matthew Neurock, Omar A. Abdelrahman, C. Daniel Frisbie, Paul J. Dauenhauer
Summary: Precise control of electron density at catalyst active sites enables regulation of surface chemistry for optimal rate and selectivity. In this study, an ultrathin catalytic film of amorphous alumina was integrated into a catalytic condenser device, allowing tunable electron depletion from the alumina active layer and increased Lewis acidity. Experimental results showed that the charged alumina surface exhibited a shift in propene formation peak temperature and a reduction in activation energy, supporting the findings from density functional theory calculations. These findings demonstrate that continuous and fast electronic control of thermocatalysis can be achieved with the catalytic condenser device.
Article
Materials Science, Multidisciplinary
Subhajit Kundu, Prafful Golani, Hwanhui Yun, Silu Guo, Khaled M. Youssef, Steven J. Koester, K. Andre Mkhoyan
Summary: Understanding interfacial reaction in metal contact formation on 2D materials is crucial for tuning the properties and efficiency of devices. Electron microscopy revealed the formation of an intermetallic contact layer, characterized by efficient edge-type charge transfer, when metals such as nickel, chromium, or titanium are deposited onto black-arsenic films.
COMMUNICATIONS MATERIALS
(2022)
