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Feng X, Bai H, Fan X, Guo M, Zhang Z, Chai G, Wang T, Xue D, Song C, Fan X. Incommensurate Spin Density Wave in Antiferromagnetic RuO_{2} Evinced by Abnormal Spin Splitting Torque. PHYSICAL REVIEW LETTERS 2024; 132:086701. [PMID: 38457714 DOI: 10.1103/physrevlett.132.086701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 12/17/2023] [Accepted: 01/23/2024] [Indexed: 03/10/2024]
Abstract
Since the discovery of antiferromagnetism, metallic oxide RuO_{2} has exhibited numerous intriguing spintronics properties such as the anomalous Hall effect and anisotropic spin splitting effect. However, the microscopic origin of its antiferromagnetism remains unclear. By investigating the spin splitting torque in RuO_{2}/Py, we found that metallic RuO_{2} exhibits a spatially periodic spin structure which interacts with the spin waves in Py through interfacial exchange coupling. The wavelength of such structure is evaluated within 14-20 nm depending on the temperature, which is evidence of an incommensurate spin density wave state in RuO_{2}. Our work not only provides a dynamics approach to characterize the antiferromagnetic ordering in RuO_{2}, but also offers fundamental insights into the spin current generation due to anisotropic spin splitting effect associated with spin density wave.
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Affiliation(s)
- Xiaoyu Feng
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Hua Bai
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Xinxin Fan
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Muhan Guo
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Zhiqiang Zhang
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Guozhi Chai
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Tao Wang
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Desheng Xue
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Cheng Song
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Xiaolong Fan
- Key Laboratory of Magnetism and Magnetic Materials (MOE), School of Physics Science and Technology, Lanzhou University, Lanzhou 730000, China
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Causer GL, Zhu H, Ionescu M, Mankey GJ, Wang XL, Klose F. Tailoring exchange bias in ferro/antiferromagnetic FePt 3 bilayers created by He + beams. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:315804. [PMID: 29964268 DOI: 10.1088/1361-648x/aad075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on artificial exchange bias created in a continuous epitaxial FePt3 film by introducing chemical disorder using a He+ beam, which features tailorable exchange bias strength through post-irradiation annealing. By design, the ferromagnetic (FM)/antiferromagnetic (AF) heterostructure exhibits stratified degrees of chemical order; however, the chemical composition and stoichiometry are invariant throughout the film volume. This uniquely allows for a consideration purely of the magnetic exchange across the FM/AF interface without the added hindrance of structural boundary parameters which inherently affect exchange bias quality. Annealing at 840 K results in the strongest exchange biased system, which displays a cross-sectional morphology of fine (<10 nm) domain structure composed of both of chemically ordered and chemically disordered domains. A magnetic model developed from fitting the characteristic polarised neutron reflectometry spectral features reveals that dual interactions can be attributed to the observed exchange bias: magnetic coupling at the FM/AF interface and also between neighbouring FM (chemically disordered) and AF (chemically ordered) domains within the nominally FM layer. Our results indicate that exchange bias is hindered at interfaces which are both chemically and magnetically perfect, while annealing can be used to balance the volume proportions of interfacial FM and AF domains to enhance the magnetic interface roughness for customisable exchange bias in mono-stoichiometric FM/AF heterostructures crafted by ion beams.
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Affiliation(s)
- Grace L Causer
- Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia. Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
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Krupin O, Rotenberg E, Kevan SD. Controlling the magnetic ground state in Cr1-x Vx films. PHYSICAL REVIEW LETTERS 2007; 99:147208. [PMID: 17930719 DOI: 10.1103/physrevlett.99.147208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2007] [Indexed: 05/25/2023]
Abstract
We demonstrate the ability to control the magnetic phase diagram of Cr1-x Vx(110) thin films grown on a W(110) substrate. Using angle-resolved photoemission, we have mapped paramagnetic and commensurate and incommensurate antiferromagnetic phases as a function of temperature, film thickness, and composition. We show that surface-localized electron states play a key role in the observed phase behaviors and suggest from this that it might be possible to control the magnetic phase by applying an external electric field.
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Affiliation(s)
- O Krupin
- 6-2100, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Won C, Wu YZ, Arenholz E, Choi J, Wu J, Qiu ZQ. Symmetry-breaking induced exchange bias in ferromagnetic Ni-Cu-Co and Ni-Fe-Co sandwiches grown on a vicinal Cu(001) surface. PHYSICAL REVIEW LETTERS 2007; 99:077203. [PMID: 17930921 DOI: 10.1103/physrevlett.99.077203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Indexed: 05/25/2023]
Abstract
Ferromagnetic Ni-Cu-Co and Ni-Fe-Co sandwiches were grown epitaxially onto a vicinal Cu(001) substrate and investigated using magneto-optical Kerr effect and x-ray magnetic circular dichroism techniques. We find that the atomic steps of the vicinal surface break the magnetic reversal symmetry to induce an exchange bias in the Ni perpendicular magnetic hysteresis loop. The Ni exchange bias direction can be switched by changing the direction of the in-plane Co magnetization. In addition, the exchange bias can be tailored by changing the Cu or Fe spacer layer thickness.
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Affiliation(s)
- C Won
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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Parker JS, Wang L, Steiner KA, Crowell PA, Leighton C. Exchange bias as a probe of the incommensurate spin-density wave in epitaxial Fe/Cr(001). PHYSICAL REVIEW LETTERS 2006; 97:227206. [PMID: 17155839 DOI: 10.1103/physrevlett.97.227206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Indexed: 05/12/2023]
Abstract
We report clear multiple period oscillations in the temperature dependence of exchange bias in an Fe thin film exchange coupled to a neighboring Cr film. The oscillations arise due to an incommensurate spin-density wave in the Cr, with wave vector perpendicular to the Fe/Cr(001) interface. The exchange bias and coercivity allow for a determination of the extent of the thermally driven wavelength expansion, the (strain-suppressed) spin-flip transition temperature, and the Cr Néel temperature, which show a crossover from bulklike to finite-size behavior at a Cr thickness of approximately 1100 A. The data are consistent with a transition from a transverse to longitudinal wave on cooling.
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Affiliation(s)
- J S Parker
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
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