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Qi J, Zhao Y, Zhang Y, Yang G, Huang H, Lyu H, Shao B, Zhang J, Li J, Zhu T, Yu G, Wei H, Zhou S, Shen B, Wang S. Full electrical manipulation of perpendicular exchange bias in ultrathin antiferromagnetic film with epitaxial strain. Nat Commun 2024; 15:4734. [PMID: 38830907 PMCID: PMC11148026 DOI: 10.1038/s41467-024-49214-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/28/2024] [Indexed: 06/05/2024] Open
Abstract
Achieving effective manipulation of perpendicular exchange bias effect remains an intricate endeavor, yet it stands a significance for the evolution of ultra-high capacity and energy-efficient magnetic memory and logic devices. A persistent impediment to its practical applications is the reliance on external magnetic fields during the current-induced switching of exchange bias in perpendicularly magnetized structures. This study elucidates the achievement of a full electrical manipulation of the perpendicular exchange bias in the multilayers with an ultrathin antiferromagnetic layer. Owing to the anisotropic epitaxial strain in the 2-nm-thick IrMn3 layer, the considerable exchange bias effect is clearly achieved at room temperature. Concomitantly, a specific global uncompensated magnetization manifests in the IrMn3 layer, facilitating the switching of the irreversible portion of the uncompensated magnetization. Consequently, the perpendicular exchange bias can be manipulated by only applying pulsed current, notably independent of the presence of any external magnetic fields.
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Affiliation(s)
- Jie Qi
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Yunchi Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Yi Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Guang Yang
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - He Huang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Haochang Lyu
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Bokai Shao
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jingyan Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jialiang Li
- Spallation Neutron Source Science Center, Dongguan, 523803, China
| | - Tao Zhu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Spallation Neutron Source Science Center, Dongguan, 523803, China
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hongxiang Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shiming Zhou
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Baogen Shen
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Shouguo Wang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China.
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Ling Y, Yu X, Yuan S, He A, Han Z, Du J, Fan Q, Yan S, Xu Q. Flexomagnetic Effect Enhanced Ferromagnetism and Magnetoelectrochemistry in Freestanding High-Entropy Alloy Films. ACS NANO 2023; 17:17299-17307. [PMID: 37643207 DOI: 10.1021/acsnano.3c05255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Freestanding thin films of functional materials enable the tuning of properties via strain and strain gradients, broadening their applications. Here, a systematic approach is proposed to fabricate freestanding CrMnFeCoNi high-entropy alloy (HEA) thin films by pulsed laser deposition using expansion-contraction of NaCl substrates and weak van der Waals interaction of the interface, which form wrinkles with inhomogeneous strain gradients when transferred to a viscous handle. We demonstrate that the nonuniform gradients of external strain (flexomagnetic effect) can induce the partial structural phase transition from FCC to BCC in the wrinkled HEA film, resulting in a 10-fold increase in its room-temperature saturation magnetization compared with the unstrained flat HEA film. Furthermore, after applying an external magnetic field, due to the different electron transfer behavior caused by the electron scattering in wrinkled and flat HEA films, their electrocatalytic magnetic responses showed a diametrically opposite picture. Our work provides a promising strategy for tuning physical and chemical properties via complex strained geometries.
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Affiliation(s)
- Yechao Ling
- School of Physics, Southeast University, Nanjing 211189, China
| | - Xiao Yu
- School of Physics, Southeast University, Nanjing 211189, China
| | - Shijun Yuan
- School of Physics, Southeast University, Nanjing 211189, China
| | - Anpeng He
- School of Physics, Southeast University, Nanjing 211189, China
| | - Zhida Han
- College of Electronic and Information Engineering, Changshu Institute of Technology, Changshu 215500, China
| | - Jun Du
- Department of Physics, Nanjing University, Nanjing 210093, China
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210008, China
| | - Qi Fan
- School of Materials Science and Enigneering, Southeast University, Nanjing 211189, China
| | - Shicheng Yan
- Jiangsu Key Laboratory for Nano Technology, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
| | - Qingyu Xu
- School of Physics, Southeast University, Nanjing 211189, China
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210008, China
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Ni-Mn-Sn-Cu Alloys after Thermal Cycling: Thermal and Magnetic Response. MATERIALS 2021; 14:ma14226851. [PMID: 34832253 PMCID: PMC8619004 DOI: 10.3390/ma14226851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/02/2021] [Accepted: 11/10/2021] [Indexed: 11/16/2022]
Abstract
Heusler Ni-Mn-Sn-based alloys are good candidates for magnetic refrigeration. This application is based on cycling processes. In this work, thermal cycles (100) have been performed in three ribbons produced by melt-spinning to check the thermal stability and the magnetic response. After cycling, the temperatures were slowly shifted and the thermodynamic properties were reduced, the entropy changed at about 3–5%. Likewise, the thermomagnetic response remains similar. Thus, these candidates maintain enough thermal stability and magnetic response after cycling. Likewise, Cu addition shifts the structural transformation to higher temperatures, whereas the Curie temperature is always near 310 K. Regarding magnetic shape memory applications, the best candidate is the Ni49Mn36 Sn14Cu1 alloy.
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Ma Y, Yang Y, Gao Y, Hu Y. Optimization of spontaneous exchange bias in Mn-rich Heusler alloys. Phys Chem Chem Phys 2021; 23:17365-17373. [PMID: 34350446 DOI: 10.1039/d1cp01797g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
At low temperature, spontaneous (zero-field-cooled, SEB) and traditional (field-cooled) exchange bias effects may be induced in a series of NiMn-based Heusler alloys, and the exchange bias is commonly sensitive to alloying elements and compositions, while the mechanisms especially for SEB are still elusive. Therefore, the SEB in Mn-rich Heusler alloys with coexistence of ferromagnetic and antiferromagnetic exchange interactions is numerically studied by performing a modified Monte Carlo simulation. The intrinsic magnetocrystalline anisotropies (KAF), exchange interactions (JFM-AF and JAF-AF), and occupation probabilities (xFM) are directly tuned to establish their dependencies of zero-field-cooled/field-cooled thermomagnetic curves and zero-field-cooled magnetization hysteresis loops. The results indicate that the freezing temperature is monotonically enhanced with increasing KAF and varies nonmonotonically with other parameters, and at 5 K, the irreversibility arising from antiferromagnetic components becomes high enough to trigger SEB even though no spin glass state exists. The SEB is nonmonotonic with KAF, JFM-AF, JAF-AF, and xFM, and its maximum value will be obtained at KAF = 4.5 × 106 J m-3, JFM-AF = 5 meV, JAF-AF = -5 meV, or xFM = 0.3. On the contrary, the coercivity is also nonmonotonic with KAF and JFM-AF while monotonic with JAF-AF and xFM. The values of the SEB field are nearly one order of magnitude smaller than those of coercivity, consistent with experimental data. The magnetic relaxation properties are calculated to propose two factors, i.e., ferromagnetic-like domain between ferromagnetic and antiferromagnetic components and decay rate, to determine the final SEB. This work demonstrates the mechanisms to optimize SEB in Mn-rich Heusler alloys, and physically the results obtained are also suitable for other material systems with spontaneous ferromagnet/antiferromagnet phase separations.
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Affiliation(s)
- Yitian Ma
- Department of Physics, College of Sciences, Northeastern University, Shenyang 110819, China.
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