1
|
Choi E, Sim KI, Burch KS, Lee YH. Emergent Multifunctional Magnetic Proximity in van der Waals Layered Heterostructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200186. [PMID: 35596612 PMCID: PMC9313546 DOI: 10.1002/advs.202200186] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/01/2022] [Indexed: 05/10/2023]
Abstract
Proximity effect, which is the coupling between distinct order parameters across interfaces of heterostructures, has attracted immense interest owing to the customizable multifunctionalities of diverse 3D materials. This facilitates various physical phenomena, such as spin order, charge transfer, spin torque, spin density wave, spin current, skyrmions, and Majorana fermions. These exotic physics play important roles for future spintronic applications. Nevertheless, several fundamental challenges remain for effective applications: unavoidable disorder and lattice mismatch limits in the growth process, short characteristic length of proximity, magnetic fluctuation in ultrathin films, and relatively weak spin-orbit coupling (SOC). Meanwhile, the extensive library of atomically thin, 2D van der Waals (vdW) layered materials, with unique characteristics such as strong SOC, magnetic anisotropy, and ultraclean surfaces, offers many opportunities to tailor versatile and more effective functionalities through proximity effects. Here, this paper focuses on magnetic proximity, i.e., proximitized magnetism and reviews the engineering of magnetism-related functionalities in 2D vdW layered heterostructures for next-generation electronic and spintronic devices. The essential factors of magnetism and interfacial engineering induced by magnetic layers are studied. The current limitations and future challenges associated with magnetic proximity-related physics phenomena in 2D heterostructures are further discussed.
Collapse
Affiliation(s)
- Eun‐Mi Choi
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
| | - Kyung Ik Sim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
| | - Kenneth S. Burch
- Department of PhysicsBoston College140 Commonwealth AveChestnut HillMA02467‐3804USA
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
- Department of Energy ScienceSungkyunkwan UniversitySuwon16419Republic of Korea
| |
Collapse
|
2
|
Bedoya-Pinto A, Ji JR, Pandeya AK, Gargiani P, Valvidares M, Sessi P, Taylor JM, Radu F, Chang K, Parkin SSP. Intrinsic 2D-XY ferromagnetism in a van der Waals monolayer. Science 2021; 374:616-620. [PMID: 34709893 DOI: 10.1126/science.abd5146] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
[Figure: see text].
Collapse
Affiliation(s)
| | - Jing-Rong Ji
- NISE Department, Max Planck Institute of Microstructure Physics, Halle, Germany
| | - Avanindra K Pandeya
- NISE Department, Max Planck Institute of Microstructure Physics, Halle, Germany
| | | | | | - Paolo Sessi
- NISE Department, Max Planck Institute of Microstructure Physics, Halle, Germany
| | - James M Taylor
- Helmholtz-Zentrum für Materialien und Energie, Berlin, Germany
| | - Florin Radu
- Helmholtz-Zentrum für Materialien und Energie, Berlin, Germany
| | - Kai Chang
- NISE Department, Max Planck Institute of Microstructure Physics, Halle, Germany
| | - Stuart S P Parkin
- NISE Department, Max Planck Institute of Microstructure Physics, Halle, Germany
| |
Collapse
|
3
|
Wang A, Peng J, Ren N, Ding L, Yu X, Wang Z, Zhao M. Spin-Gapless States in Two-Dimensional Molecular Ferromagnet Fe 2(TCNQ) 2. J Phys Chem Lett 2021; 12:7921-7927. [PMID: 34384211 DOI: 10.1021/acs.jpclett.1c01869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional van der Waals magnetic atomic crystals have provided unprecedented access to magnetic ground states due to a quantum confinement effect. Here, using first-principles calculations, we demonstrate a spin-gapless molecular ferromagnet, namely, Fe2(TCNQ)2, with superior mechanical stability and a remarkable linear Dirac cone, which can be exfoliated from its already-synthesized van der Waals crystal. Especially, Young's modulus has values of 175.28 GPa·nm along the x- and y-directions with a Poisson's ratio of 0.29, while the Curie temperature within the Ising model is considerably higher than room temperature. Furthermore, spin-orbit coupling can open a band gap at the Dirac point, leading to topologically nontrivial electronic states characterized by an integer value of the Chern number and the edge states of its nanoribbon. Our results offer versatile platforms for achieving plastic spin filtering or a quantum anomalous Hall effect with promising applications in spintronics devices.
Collapse
Affiliation(s)
- Aizhu Wang
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Jingyang Peng
- School of Science, Royal Melbourne Institute of Technology University, Melbourne, Victoria 3001, Australia
| | - Na Ren
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Longhua Ding
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Xin Yu
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Zhenhai Wang
- College of Telecommunications & Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210003, China
| | - Mingwen Zhao
- School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| |
Collapse
|
4
|
Chakraborty S, Ravikumar A. Substrate induced electronic phase transitions of CrI[Formula: see text] based van der Waals heterostructures. Sci Rep 2021; 11:198. [PMID: 33420187 PMCID: PMC7794430 DOI: 10.1038/s41598-020-80290-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/14/2020] [Indexed: 11/09/2022] Open
Abstract
We perform first principle density functional theory calculations to predict the substrate induced electronic phase transitions of CrI[Formula: see text] based 2-D heterostructures. We adsorb graphene and MoS[Formula: see text] on novel 2-D ferromagnetic semiconductor-CrI[Formula: see text] and investigate the electronic and magnetic properties of these heterostructures with and without spin orbit coupling (SOC). We find that when strained MoS[Formula: see text] is adsorbed on CrI[Formula: see text], the spin dependent band gap which is a characteristic of CrI[Formula: see text], ceases to remain. The bandgap of the heterostructure reduces drastically ([Formula: see text] 70%) and the heterostructure shows an indirect, spin-independent bandgap of [Formula: see text] 0.5 eV. The heterostructure remains magnetic (with and without SOC) with the magnetic moment localized primarily on CrI[Formula: see text]. Adsorption of graphene on CrI[Formula: see text] induces an electronic phase transition of the subsequent heterostructure to a ferromagnetic metal in both the spin configurations with magnetic moment localized on CrI[Formula: see text]. The SOC induced interaction opens a bandgap of [Formula: see text] 30 meV in the Dirac cone of graphene, which allows us to visualize Chern insulating states without reducing van der Waals gap.
Collapse
Affiliation(s)
- Shamik Chakraborty
- Nanoelectronics Research Laboratory, Department of Electronics and Communication Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Bengaluru, 560035 India
| | - Abhilash Ravikumar
- Nanoelectronics Research Laboratory, Department of Electronics and Communication Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Bengaluru, 560035 India
| |
Collapse
|
5
|
Singla R, Hackett TA, Kumar S, Sharma J, Kashyap MK. Curie temperature engineering in a novel 2D analog of iron ore (hematene) via strain. NANOSCALE ADVANCES 2020; 2:5890-5896. [PMID: 36133873 PMCID: PMC9417893 DOI: 10.1039/d0na00556h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 10/26/2020] [Indexed: 06/13/2023]
Abstract
As a newly exfoliated magnetic 2D material from hematite, hematene is the most far-reaching ultrathin magnetic indirect bandgap semiconductor. We have carried out a detailed structural analysis of hematene via prefacing strain by means of first-principles calculations based on density functional theory (DFT). Hematene in the pristine form emerges out to be a magnetic semiconductor with a bandgap of 1.0/2.0 eV for the majority/minority spin channel. The dependence of magnetic anisotropy energy (MAE), T C, and the bandgap on compressive and tensile strains has been scanned exclusively. It is examined that T C depends firmly on the compressive strain and increases up to 21.1% at a compressive strain of 6% whereas it decreases significantly for tensile strain. The MAE is negatively correlated with the tensile and compressive strain. The value of MAE for all compressive strain cases is more than that of the pristine hematene. These results summarize that the studied 2D hematene has broad application prospects in spintronics, memory-based devices, and valleytronics.
Collapse
Affiliation(s)
- Renu Singla
- Department of Physics, Kurukshetra University Kurukshetra 136119 Haryana India +91-1744-238277 +91-1744-238410 extn 2482
| | - Timothy A Hackett
- Department of Biochemistry, University of Nebraska-Lincoln Lincoln Nebraska 68588-0664 USA
| | - Sarvesh Kumar
- Inter-University Accelerator Centre (IUAC) Aruna Asaf Ali Marg New Delhi 110067 India
| | - Jyotsna Sharma
- Department of Physics, Amity School of Applied Sciences, Amity University Haryana Gurugram 122413 India
| | - Manish K Kashyap
- Department of Physics, Kurukshetra University Kurukshetra 136119 Haryana India +91-1744-238277 +91-1744-238410 extn 2482
| |
Collapse
|
6
|
Liu L, Chen S, Lin Z, Zhang X. A Symmetry-Breaking Phase in Two-Dimensional FeTe 2 with Ferromagnetism above Room Temperature. J Phys Chem Lett 2020; 11:7893-7900. [PMID: 32787292 DOI: 10.1021/acs.jpclett.0c01911] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recently, ferromagnetism observed in monolayer two-dimensional (2D) materials has attracted attention due to the promise of its application in next-generation spintronics. Here, we predict a symmetry-breaking phase in 2D FeTe2 that differs from conventional transition metal ditellurides shows superior stability and room-temperature ferromagnetism. Through density functional theory calculations, we find the exchange interactions in FeTe2 consist of short-range superexchange and long-range oscillatory exchanges mediated by itinerant electrons. For six nearest neighbors, the exchange constants are calculated to be 50.95, 33.41, 2.70, 11.02, 14.46, and -4.12 meV. Furthermore, the strong relativistic effects on Te2+ induce giant out-of-plane exchange anisotropy and open up a significantly large spin wave gap (ΔSW) of 1.22 meV. All of this leads to robust ferromagnetism with the Tc surpassing 423 K, which is predicted by the renormalization group Monte Carlo method, sufficiently higher than room temperature. Our findings shed light on the promising future of FeTe2 in 2D magnetic research and spintronic applications.
Collapse
Affiliation(s)
- Liang Liu
- Institute of Nanosurface Science and Engineering, Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, Shenzhen University, Shenzhen 518060, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Songsong Chen
- Institute of Nanosurface Science and Engineering, Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, Shenzhen University, Shenzhen 518060, China
| | - Zezhou Lin
- Institute of Nanosurface Science and Engineering, Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, Shenzhen University, Shenzhen 518060, China
| | - Xi Zhang
- Institute of Nanosurface Science and Engineering, Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, Shenzhen University, Shenzhen 518060, China
| |
Collapse
|
7
|
Schlenhoff A, Krause S, Wiesendanger R. Step-Edge-Induced Anisotropic Chiral Spin Coupling in Ultrathin Magnetic Films. PHYSICAL REVIEW LETTERS 2019; 123:037201. [PMID: 31386468 DOI: 10.1103/physrevlett.123.037201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Indexed: 06/10/2023]
Abstract
Step edges represent a local break of lateral symmetry in ultrathin magnetic films. In our experiments, we investigate the spin coupling across atomic step edges on Fe/W(110) by means of spin-polarized scanning tunneling microscopy and spectroscopy. Local modifications of the spin texture toward step edges separating double from single layer areas are observed, and selection rules indicate a chiral spin coupling that significantly changes with the propagation along the [11[over ¯]0] or the [001] crystallographic direction. The findings are explained via anisotropic Dzyaloshinskii-Moriya interactions arising from the broken lateral symmetry at atomic step edges.
Collapse
Affiliation(s)
- A Schlenhoff
- Department of Physics, University of Hamburg, Jungiusstrasse 11A, 20355 Hamburg, Germany
| | - S Krause
- Department of Physics, University of Hamburg, Jungiusstrasse 11A, 20355 Hamburg, Germany
| | - R Wiesendanger
- Department of Physics, University of Hamburg, Jungiusstrasse 11A, 20355 Hamburg, Germany
| |
Collapse
|
8
|
Li H, Ruan S, Zeng YJ. Intrinsic Van Der Waals Magnetic Materials from Bulk to the 2D Limit: New Frontiers of Spintronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900065. [PMID: 31069896 DOI: 10.1002/adma.201900065] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/21/2019] [Indexed: 05/22/2023]
Abstract
2D van der Waals (vdW) magnets, which present intrinsic ferromagnetic/antiferromagnetic ground states at finite temperatures down to atomic-layer thicknesses, open a new horizon in materials science and enable the potential development of new spin-related applications. The layered structure of vdW magnets facilitates their atomic-layer cleavability and magnetic anisotropy, which counteracts spin fluctuations, thereby providing an ideal platform for theoretically and experimentally exploring magnetic phase transitions in the 2D limit. With reduced dimensions, the susceptibility of 2D magnets to a large variety of external stimuli also makes them more promising than their bulk counterpart in various device applications. Here, the current status of characterization and tuning of the magnetic properties of 2D vdW magnets, particularly the atomic-layer thickness, is presented. Various state-of-the-art optical and electrical techniques have been applied to reveal the magnetic states of 2D vdW magnets. Other emerging 2D vdW magnets and future perspectives on the stacking strategy are also given; it is believed that they will excite more intensive research and provide unprecedented opportunities in the field of spintronics.
Collapse
Affiliation(s)
- Hui Li
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
- Center for Advanced Material Diagnostic Technology, Shenzhen Technology University, Shenzhen, 518118, P. R. China
| | - Shuangchen Ruan
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Yu-Jia Zeng
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| |
Collapse
|
9
|
Jin W, Kim HH, Ye Z, Li S, Rezaie P, Diaz F, Siddiq S, Wauer E, Yang B, Li C, Tian S, Sun K, Lei H, Tsen AW, Zhao L, He R. Raman fingerprint of two terahertz spin wave branches in a two-dimensional honeycomb Ising ferromagnet. Nat Commun 2018; 9:5122. [PMID: 30504853 PMCID: PMC6269484 DOI: 10.1038/s41467-018-07547-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/08/2018] [Indexed: 11/29/2022] Open
Abstract
Two-dimensional (2D) magnetism has been long sought-after and only very recently realized in atomic crystals of magnetic van der Waals materials. So far, a comprehensive understanding of the magnetic excitations in such 2D magnets remains missing. Here we report polarized micro-Raman spectroscopy studies on a 2D honeycomb ferromagnet CrI3. We show the definitive evidence of two sets of zero-momentum spin waves at frequencies of 2.28 terahertz (THz) and 3.75 THz, respectively, that are three orders of magnitude higher than those of conventional ferromagnets. By tracking the thickness dependence of both spin waves, we reveal that both are surface spin waves with lifetimes an order of magnitude longer than their temporal periods. Our results of two branches of high-frequency, long-lived surface spin waves in 2D CrI3 demonstrate intriguing spin dynamics and intricate interplay with fluctuations in the 2D limit, thus opening up opportunities for ultrafast spintronics incorporating 2D magnets. Characteristics of spin waves in recently discovered two-dimensional (2D) Ising ferromagnets are still lacking. Here, Jin and Kim et al. report Raman resonance evidence of two sets of surface spin waves in the 2D honeycomb ferromagnet CrI3.
Collapse
Affiliation(s)
- Wencan Jin
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan, 48109, USA
| | - Hyun Ho Kim
- Institute for Quantum Computing, Department of Chemistry, and Department of Physics and Astronomy, University of Waterloo, Waterloo, 200 University Ave W, Ontario, N2L 3G1, Canada
| | - Zhipeng Ye
- Department of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas, 79409, USA
| | - Siwen Li
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan, 48109, USA
| | - Pouyan Rezaie
- Department of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas, 79409, USA
| | - Fabian Diaz
- Department of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas, 79409, USA
| | - Saad Siddiq
- Department of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas, 79409, USA
| | - Eric Wauer
- Department of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas, 79409, USA
| | - Bowen Yang
- Institute for Quantum Computing, Department of Chemistry, and Department of Physics and Astronomy, University of Waterloo, Waterloo, 200 University Ave W, Ontario, N2L 3G1, Canada
| | - Chenghe Li
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - Shangjie Tian
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - Kai Sun
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan, 48109, USA
| | - Hechang Lei
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - Adam W Tsen
- Institute for Quantum Computing, Department of Chemistry, and Department of Physics and Astronomy, University of Waterloo, Waterloo, 200 University Ave W, Ontario, N2L 3G1, Canada
| | - Liuyan Zhao
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan, 48109, USA.
| | - Rui He
- Department of Electrical and Computer Engineering, Texas Tech University, 910 Boston Avenue, Lubbock, Texas, 79409, USA.
| |
Collapse
|
10
|
Burch KS, Mandrus D, Park JG. Magnetism in two-dimensional van der Waals materials. Nature 2018; 563:47-52. [DOI: 10.1038/s41586-018-0631-z] [Citation(s) in RCA: 664] [Impact Index Per Article: 110.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/20/2018] [Indexed: 11/09/2022]
|
11
|
Deng Y, Yu Y, Song Y, Zhang J, Wang NZ, Sun Z, Yi Y, Wu YZ, Wu S, Zhu J, Wang J, Chen XH, Zhang Y. Gate-tunable room-temperature ferromagnetism in two-dimensional Fe3GeTe2. Nature 2018; 563:94-99. [DOI: 10.1038/s41586-018-0626-9] [Citation(s) in RCA: 1076] [Impact Index Per Article: 179.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/07/2018] [Indexed: 11/09/2022]
|
12
|
O'Hara DJ, Zhu T, Trout AH, Ahmed AS, Luo YK, Lee CH, Brenner MR, Rajan S, Gupta JA, McComb DW, Kawakami RK. Room Temperature Intrinsic Ferromagnetism in Epitaxial Manganese Selenide Films in the Monolayer Limit. NANO LETTERS 2018; 18:3125-3131. [PMID: 29608316 DOI: 10.1021/acs.nanolett.8b00683] [Citation(s) in RCA: 199] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Monolayer van der Waals (vdW) magnets provide an exciting opportunity for exploring two-dimensional (2D) magnetism for scientific and technological advances, but the intrinsic ferromagnetism has only been observed at low temperatures. Here, we report the observation of room temperature ferromagnetism in manganese selenide (MnSe x) films grown by molecular beam epitaxy (MBE). Magnetic and structural characterization provides strong evidence that, in the monolayer limit, the ferromagnetism originates from a vdW manganese diselenide (MnSe2) monolayer, while for thicker films it could originate from a combination of vdW MnSe2 and/or interfacial magnetism of α-MnSe(111). Magnetization measurements of monolayer MnSe x films on GaSe and SnSe2 epilayers show ferromagnetic ordering with a large saturation magnetization of ∼4 Bohr magnetons per Mn, which is consistent with the density functional theory calculations predicting ferromagnetism in monolayer 1T-MnSe2. Growing MnSe x films on GaSe up to a high thickness (∼40 nm) produces α-MnSe(111) and an enhanced magnetic moment (∼2×) compared to the monolayer MnSe x samples. Detailed structural characterization by scanning transmission electron microscopy (STEM), scanning tunneling microscopy (STM), and reflection high energy electron diffraction (RHEED) reveals an abrupt and clean interface between GaSe(0001) and α-MnSe(111). In particular, the structure measured by STEM is consistent with the presence of a MnSe2 monolayer at the interface. These results hold promise for potential applications in energy efficient information storage and processing.
Collapse
Affiliation(s)
- Dante J O'Hara
- Materials Science and Engineering , University of California , Riverside , California 92521 , United States
| | - Tiancong Zhu
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Amanda H Trout
- Center for Electron Microscopy and Analysis , The Ohio State University , Columbus , Ohio 43212 , United States
- Department of Materials Science and Engineering , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Adam S Ahmed
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Yunqiu Kelly Luo
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Choong Hee Lee
- Department of Electrical and Computer Engineering , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Mark R Brenner
- Department of Electrical and Computer Engineering , The Ohio State University , Columbus , Ohio 43210 , United States
- Semiconductor Epitaxy and Analysis Laboratory , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Siddharth Rajan
- Department of Materials Science and Engineering , The Ohio State University , Columbus , Ohio 43210 , United States
- Department of Electrical and Computer Engineering , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Jay A Gupta
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - David W McComb
- Center for Electron Microscopy and Analysis , The Ohio State University , Columbus , Ohio 43212 , United States
- Department of Materials Science and Engineering , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Roland K Kawakami
- Materials Science and Engineering , University of California , Riverside , California 92521 , United States
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| |
Collapse
|
13
|
Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature 2017; 546:270-273. [DOI: 10.1038/nature22391] [Citation(s) in RCA: 2613] [Impact Index Per Article: 373.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 04/20/2017] [Indexed: 01/20/2023]
|
14
|
Zakeri K. Probing of the interfacial Heisenberg and Dzyaloshinskii-Moriya exchange interaction by magnon spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:013001. [PMID: 27831928 DOI: 10.1088/0953-8984/29/1/013001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This Topical Review presents an overview of the recent experimental results on the quantitative determination of the magnetic exchange parameters in ultrathin magnetic films and multilayers grown on different substrates. The experimental approaches for probing both the symmetric Heisenberg and the antisymmetric Dzyaloshinskii-Moriya exchange interaction in ultrathin magnetic films and at interfaces are discussed in detail. It is explained how the experimental spectrum of magnetic excitations can be used to quantify the strength of these interactions.
Collapse
Affiliation(s)
- Khalil Zakeri
- Heisenberg Spin-dynamics Group, Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe, Germany. Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| |
Collapse
|
15
|
Honma K, Sato T, Souma S, Sugawara K, Tanaka Y, Takahashi T. Switching of Dirac-Fermion Mass at the Interface of Ultrathin Ferromagnet and Rashba Metal. PHYSICAL REVIEW LETTERS 2015; 115:266401. [PMID: 26765009 DOI: 10.1103/physrevlett.115.266401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Indexed: 06/05/2023]
Abstract
We have performed spin- and angle-resolved photoemission spectroscopy on tungsten (110) interfaced with an ultrathin iron (Fe) layer to study an influence of ferromagnetism on the Dirac-cone-like surface-interface states. We found an unexpectedly large energy gap of 340 meV at the Dirac point, and have succeeded in switching the Dirac-fermion mass by controlling the direction of Fe spins (in plane or out of plane) through tuning the thickness of the Fe overlayer or adsorbing oxygen on it. Such a manipulation of Dirac-fermion mass via the magnetic proximity effect opens a promising platform for realizing new spintronic devices utilizing a combination of exchange and Rashba-spin-orbit interactions.
Collapse
Affiliation(s)
- K Honma
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| | - T Sato
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| | - S Souma
- WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - K Sugawara
- WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Y Tanaka
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| | - T Takahashi
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
- WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| |
Collapse
|
16
|
Etz C, Bergqvist L, Bergman A, Taroni A, Eriksson O. Atomistic spin dynamics and surface magnons. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:243202. [PMID: 26030259 DOI: 10.1088/0953-8984/27/24/243202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Atomistic spin dynamics simulations have evolved to become a powerful and versatile tool for simulating dynamic properties of magnetic materials. It has a wide range of applications, for instance switching of magnetic states in bulk and nano-magnets, dynamics of topological magnets, such as skyrmions and vortices and domain wall motion. In this review, after a brief summary of the existing investigation tools for the study of magnons, we focus on calculations of spin-wave excitations in low-dimensional magnets and the effect of relativistic and temperature effects in such structures. In general, we find a good agreement between our results and the experimental values. For material specific studies, the atomistic spin dynamics is combined with electronic structure calculations within the density functional theory from which the required parameters are calculated, such as magnetic exchange interactions, magnetocrystalline anisotropy, and Dzyaloshinskii-Moriya vectors.
Collapse
Affiliation(s)
- Corina Etz
- Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden. Department of Engineering Sciences and Mathematics, Luleå University of Technology, 971 87 Luleå, Sweden
| | | | | | | | | |
Collapse
|
17
|
Udvardi L, Szunyogh L. Chiral asymmetry of the spin-wave spectra in ultrathin magnetic films. PHYSICAL REVIEW LETTERS 2009; 102:207204. [PMID: 19519069 DOI: 10.1103/physrevlett.102.207204] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Indexed: 05/27/2023]
Abstract
We raise the possibility that the chiral degeneracy of the magnons in ultrathin films can be lifted due to the presence of Dzyaloshinskii-Moriya interactions. By using simple symmetry arguments, we discuss under which conditions such a chiral asymmetry occurs. We then perform relativistic first principles calculations for an Fe monolayer on W(110) and explicitly reveal the asymmetry of the spin-wave spectrum in the case of wave vectors parallel to the (001) direction. Furthermore, we quantitatively interpret our results in terms of a simplified spin model by using calculated Dzyaloshinskii-Moriya vectors. Our theoretical prediction should inspire experiments to explore the asymmetry of spin waves, with a particular emphasis on the possibility to measure the Dzyaloshinskii-Moriya interactions in ultrathin films.
Collapse
Affiliation(s)
- L Udvardi
- Department of Theoretical Physics, Budapest University of Technology and Economics, H1111 Budapest, Hungary
| | | |
Collapse
|
18
|
Prokop J, Tang WX, Zhang Y, Tudosa I, Peixoto TRF, Zakeri K, Kirschner J. Magnons in a ferromagnetic monolayer. PHYSICAL REVIEW LETTERS 2009; 102:177206. [PMID: 19518825 DOI: 10.1103/physrevlett.102.177206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Indexed: 05/27/2023]
Abstract
We report the first observation of high wave vector magnon excitations in a ferromagnetic monolayer. Using spin-polarized electron energy loss spectroscopy, we observed the magnon dispersion in one atomic layer (ML) of Fe on W(110) at 120 K. The magnon energies are small in comparison to the bulk and surface Fe(110) excitations. We find an exchange parameter and magnetic anisotropy similar to that from static measurements. Our results are in sharp contrast to theoretical calculations, indicating that the present understanding of magnetism of the ML Fe requires considerable revision.
Collapse
Affiliation(s)
- J Prokop
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | | | | | | | | | | | | |
Collapse
|
19
|
Taroni A, Bramwell ST, Holdsworth PCW. Universal window for two-dimensional critical exponents. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:275233. [PMID: 21694394 DOI: 10.1088/0953-8984/20/27/275233] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Two-dimensional condensed matter is realized in increasingly diverse forms that are accessible to experiment and of potential technological value. The properties of these systems are influenced by many length scales and reflect both generic physics and chemical detail. To unify their physical description is therefore a complex and important challenge. Here we investigate the distribution of experimentally estimated critical exponents, β, that characterize the evolution of the order parameter through the ordering transition. The distribution is found to be bimodal and bounded within a window ∼0.1≤β≤0.25, facts that are only in partial agreement with the established theory of critical phenomena. In particular, the bounded nature of the distribution is impossible to reconcile with the existing theory for one of the major universality classes of two-dimensional behaviour-the XY model with four-fold crystal field-which predicts a spectrum of non-universal exponents bounded only from below. Through a combination of numerical and renormalization group arguments we resolve the contradiction between theory and experiment and demonstrate how the 'universal window' for critical exponents observed in experiment arises from a competition between marginal operators.
Collapse
Affiliation(s)
- A Taroni
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | | | | |
Collapse
|
20
|
Dick R. A Model System for Dimensional Competition in Nanostructures: A Quantum Wire on a Surface. NANOSCALE RESEARCH LETTERS 2008; 3:140-144. [PMCID: PMC3244799 DOI: 10.1007/s11671-008-9126-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 03/13/2008] [Indexed: 05/30/2023]
Abstract
The retarded Green’s function (E−H + iε)−1is given for a dimensionally hybrid Hamiltonian which interpolates between one and two dimensions. This is used as a model for dimensional competition in propagation effects in the presence of one-dimensional subsystems on a surface. The presence of a quantum wire generates additional exponential terms in the Green’s function. The result shows how the location of the one-dimensional subsystem affects propagation of particles.
Collapse
Affiliation(s)
- Rainer Dick
- Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, SK, Canada, S7N 5E2
| |
Collapse
|
21
|
Pärnaste M, Marcellini M, Holmström E, Bock N, Fransson J, Eriksson O, Hjörvarsson B. Dimensionality crossover in the induced magnetization of Pd layers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:246213. [PMID: 21694056 DOI: 10.1088/0953-8984/19/24/246213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The magnetic ordering of a series of samples consisting of ultrathin Fe layers embedded in Pd was investigated using the magneto-optical Kerr effect. The samples consisted of a single Fe layer with nominal thickness 0.2≤d(Fe)≤1.6 monolayers sandwiched between two 20 monolayer Pd layers. A dimensionality crossover from two dimensions to three dimensions occurs as d(Fe) is increased from 0.4 to 1.0 monolayers. First-principles calculations were performed in order to determine the magnetic profile, and we used a spin-wave quantum well model for obtaining a qualitative description of the dimensionality crossover. The results clearly prove the existence of a dimensionality crossover in the induced magnetization, opening new routes for addressing the influence of extension on order.
Collapse
Affiliation(s)
- Martin Pärnaste
- Department of Physics, Uppsala University, Box 530, 751 21 Uppsala, Sweden
| | | | | | | | | | | | | |
Collapse
|
22
|
|
23
|
Pratzer M, Elmers HJ, Bode M, Pietzsch O, Kubetzka A, Wiesendanger R. Atomic-scale magnetic domain walls in quasi-one-dimensional Fe nanostripes. PHYSICAL REVIEW LETTERS 2001; 87:127201. [PMID: 11580546 DOI: 10.1103/physrevlett.87.127201] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2001] [Indexed: 05/23/2023]
Abstract
Fe nanostripes on W(110) are investigated by Kerr magnetometry and spin-polarized scanning tunneling microscopy (SP-STM). An Arrhenius law is observed for the temperature dependent magnetic susceptibility indicating a one-dimensional magnetic behavior. The activation energy for creating antiparallel spin blocks indicates extremely narrow domain walls with a width on a length scale of the lattice constant. This is confirmed by imaging the domain wall by SP-STM. This information allows the quantification of the exchange stiffness and the anisotropy constant.
Collapse
Affiliation(s)
- M Pratzer
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | | | | | | | | | | |
Collapse
|
24
|
Röhlsberger R, Bansmann J, Senz V, Jonas KL, Bettac A, Leupold O, Rüffer R, Burkel E, Meiwes-Broer KH. Perpendicular spin orientation in ultrasmall Fe islands on W(110). PHYSICAL REVIEW LETTERS 2001; 86:5597-5600. [PMID: 11415310 DOI: 10.1103/physrevlett.86.5597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2000] [Indexed: 05/23/2023]
Abstract
We have studied the magnetism of Ag-coated Fe islands on W(110) by nuclear resonant scattering of synchrotron radiation at the 14.4 keV resonance of (57)Fe. Separated islands with an average diameter of 2.0 nm and monolayer thickness are formed at a Fe coverage of theta = 0.57 bulk monolayers. Time spectra of the nuclear decay were measured in the temperature range from 4.5 to 300 K. We find strong evidence for perpendicular spin orientation, which most likely results from the interplay of shape anisotropy and elastic strain in the islands.
Collapse
Affiliation(s)
- R Röhlsberger
- Universität Rostock, Fachbereich Physik, Universitätsplatz 3, 18055 Rostock, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|