Temperature-robust exchange bias and spin-orbit torque switching in van der Waals heterostructure

Abstract

Exchange bias (EB) in ferromagnetic/antiferromagnetic materials is a novel idea for high-density spintronic devices. Van der Waals (vdW) heterostructures offer a promising solution, enabling a “Lego” like assembly without interface or adding dopants, opposite to traditional heterostructures. However, in typical vdW heterostructures, the EB effect exists at low temperatures and only one polarity. This work addresses these challenges by using Fe₃GaTe₂/NiPS₃ heterostructures whose EB can survive at higher temperatures and polarities flip. The exchange bias (EB) of the device persists up to 150 K and can have its polarity reversed by altering the stacking direction during fabrication. Simultaneously, an anomalous Hall effect (AHE) with a coercive field of approximately 0.9 T is observed at 5 K and remains detectable up to 300 K. The device further shows the spin-orbit torque (SOT)-induced magnetization switching up to room temperature. Under low field-cooling conditions (e.g., ≥2 mT), we observe an EB field (H_EB) up to 1 mT, which reached 110 mT at 1.5 T. H_EB becomes zero above 150 K, showing a non-discernible EB effect, whereas the AHE persists up to room temperature. Similarly, in the Fe₃GaTe₂/NiPS₃ and NiPS₃/Fe₃GaTe₂, different stacking layers at the interface induce the net magnetic effect and flip the magnetization direction due to magnetic domains at the Fe₃GaTe₂ layer. The results show that strong interlayer coupling within these layers generates significant AHE and high H_EB with blocking temperatures up to 150 K, making it suitable for the new 2D spintronic device applications.

Keywords

2D van der Waals / exchange interaction / magnetic domains / spin-orbit torque switching / spintronic devices

References

[1] Wu Y, Zhang S, Zhang J, et al. Néel-type skyrmion in WTe₂/Fe₃GeTe₂ van der Waals heterostructure. Nat Commun. 2020; 11(1): 3860.

[2] Xiao H, Lyu B, Mi M, et al. Polarity-reversal of exchange bias in van der Waals FePS₃/Fe₃GaTe₂ heterostructures. Adv Sci. 2024; 11(11):2409210.

[3] Wu Y, Francisco B, Chen Z, et al. A van der Waals interface hosting two groups of magnetic skyrmions. Adv Mater. 2022; 34(16):2110583.

[4] Li K, Wang L, Wang Y, et al. Electric field switching of magnon spin current in a compensated ferrimagnet. Adv Mater. 2024; 36(21):2312137.

[5] Qi W, Fei F, Zhang Z, et al. Exchange bias in heterostructures combining magnetic topological insulator MnBi₂Te₄ and metallic ferromagnet Fe₃GeTe₂. Appl Phys Lett. 2024; 125(2):023101.

[6] Wang Z, Sapkota D, Taniguchi T, Watanabe K, Mandrus D, Morpurgo AF. Tunneling spin valves based on Fe₃GeTe₂/hBN/Fe₃GeTe₂ van der Waals heterostructures. Nano Lett. 2018; 18(7): 4303-4308.

[7] Albarakati S, Tan C, Chen Z-J, et al. Antisymmetric magnetoresistance in van der Waals Fe₃GeTe₂/graphite/Fe₃GeTe₂ trilayer heterostructures. Sci Adv. 2019; 5(7):eaaw0409.

[8] Song T, Fei Z, Yankowitz M, et al. Switching 2D magnetic states via pressure tuning of layer stacking. Nat Mater. 2019; 18(12): 1298-1302.

[9] Wang M, Cai W, Zhu D, et al. Field-free switching of a perpendicular magnetic tunnel junction through the interplay of spin-orbit and spin-transfer torques. Nat Electron. 2018; 1(11): 582-588.

[10] Lin X, Yang W, Wang KL, Zhao W. Two-dimensional spintronics for low-power electronics. Nat Electron. 2019; 2(7): 274-283.

[11] Guo Z, Yin J, Bai Y, et al. Spintronics for energy-efficient computing: an overview and outlook. Proc IEEE. 2021; 109(8): 1398-1417.

[12] Chen B, Fei F, Zhang D, et al. Intrinsic magnetic topological insulator phases in the Sb doped MnBi₂Te₄ bulks and thin flakes. Nat Commun. 2019; 10(1): 4469.

[13] Jin W, Li X, Zhang G, et al. Tunable high-temperature tunneling magnetoresistance in all-van der Waals antiferromagnet/semiconductor/ferromagnet junctions. Adv Funct Mater. 2024; 34(37):2402091.

[14] Huang X, Zhang L, Tong L, et al. Manipulating exchange bias in 2D magnetic heterojunction for high-performance robust memory applications. Nat Commun. 2023; 14(1): 2190.

[15] Jo J, Calavalle F, Martín-García B, et al. Exchange bias in molecule/Fe₃GeTe₂ van der Waals heterostructures via spinterface effects. Adv Mater. 2022; 34(21):2200474.

[16] Ostwal V, Shen T, Appenzeller J. Efficient spin-orbit torque switching of the semiconducting van der Waals ferromagnet Cr₂Ge₂Te₆. Adv Mater. 2020; 32(7):1906021.

[17] Peng S, Zhu D, Li W, et al. Exchange bias switching in an antiferromagnet/ferromagnet bilayer driven by spin-orbit torque. Nat Electron. 2020; 3(12): 757-764.

[18] Cham TMJ, Dorrian RJ, Zhang XS, et al. Exchange bias between van der Waals materials: tilted magnetic states and field-free spin-orbit-torque switching. Adv Mater. 2024; 36(13):e2305739.

[19] Du A, Zhu D, Cao K, et al. Electrical manipulation and detection of antiferromagnetism in magnetic tunnel junctions. Nat Electron. 2023; 6(6): 425-433.

[20] Hu C, Gordon KN, Liu P, et al. A van der Waals antiferromagnetic topological insulator with weak interlayer magnetic coupling. Nat Commun. 2020; 11(1): 97.

[21] Mortelmans W, De Gendt S, Heyns M, Merckling C. Epitaxy of 2D chalcogenides: aspects and consequences of weak van der Waals coupling. Appl Mater Today. 2021; 22:100975.

[22] Xia J, Yan J, Wang Z, et al. Strong coupling and pressure engineering in WSe₂–MoSe₂ heterobilayers. Nat Phys. 2021; 17(1): 92-98.

[23] Zhu R, Zhang W, Shen W, et al. Exchange bias in van der Waals CrCl₃/Fe₃GeTe₂ heterostructures. Nano Lett. 2020; 20(7): 5030-5035.

[24] Hu G, Zhu Y, Xiang J, et al. Antisymmetric magnetoresistance in a van der Waals antiferromagnetic/ferromagnetic layered MnPS₃/Fe₃GeTe₂ stacking heterostructure. ACS Nano. 2020; 14(9): 12037-12044.

[25] Dai H, Cheng H, Cai M, et al. Enhancement of the coercive field and exchange bias effect in Fe₃GeTe₂/MnPX₃ (X = S and Se) van der Waals heterostructures. ACS Appl Mater Interfaces. 2021; 13(20): 24314-24320.

[26] Gu K, Zhang X, Liu X, et al. Exchange bias modulated by antiferromagnetic spin-flop transition in 2D van der Waals heterostructures. Adv Sci. 2024; 11(17):2307034.

[27] Puthirath Balan A, Kumar A, Scholz T, et al. Harnessing van der Waals CrPS₄ and surface oxides for nonmonotonic preset field induced exchange bias in Fe₃GeTe₂. ACS Nano. 2024; 18(11): 8383-8391.

[28] Zhang T, Zhang Y, Huang M, et al. Tuning the exchange bias effect in 2D van der Waals ferro-/antiferromagnetic Fe₃GeTe₂/CrOCl heterostructures. Adv Sci. 2022; 9(11):2105483.

[29] Albarakati S, Xie W-Q, Tan C, et al. Electric control of exchange bias effect in FePS₃–Fe₅GeTe₂ van der Waals heterostructures. Nano Lett. 2022; 22(15): 6166-6172.

[30] Ying Z, Chen B, Li C, et al. Large exchange bias effect and coverage-dependent interfacial coupling in CrI₃/MnBi₂Te₄ van der Waals heterostructures. Nano Lett. 2023; 23(3): 765-771.

[31] Zhang L, Huang X, Dai H, et al. Proximity-coupling-induced significant enhancement of coercive field and curie temperature in 2D van der Waals heterostructures. Adv Mater. 2020; 32(38):2002032.

[32] Zheng G, Xie W-Q, Albarakati S, et al. Gate-tuned interlayer coupling in van der Waals ferromagnet Fe₃GeTe₂ nanoflakes. Phys Rev Lett. 2020; 125(4):047202.

[33] Wu Y, Wang W, Pan L, Wang KL. Manipulating exchange bias in a van der Waals ferromagnet. Adv Mater. 2022; 34(12):2105266.

[34] van den Brink A, Vermijs G, Solignac A, et al. Field-free magnetization reversal by spin-Hall effect and exchange bias. Nat Commun. 2016; 7(1):10854.

[35] Oh Y-W, Baek C S-h, Kim YM, et al. Field-free switching of perpendicular magnetization through spin-orbit torque in antiferromagnet/ferromagnet/oxide structures. Nat Nanotechnol. 2016; 11(10): 878-884.

[36] Deepak KA, Yusuf SM. Intertwined magnetization and exchange bias reversals across compensation temperature in YbCrO₃ compound. Phys Rev Mater. 2021; 5(12):124402.

[37] Hong F, Cheng Z, Wang X, Dou S. Competition between the crystal field and the exchange field in Er³⁺ doped NdMnO₃. Appl Phys Lett. 2012; 101(12):121913.

[38] Zhang G, Guo F, Wu H, et al. Above-room-temperature strong intrinsic ferromagnetism in 2D van der Waals Fe₃GaTe₂ with large perpendicular magnetic anisotropy. Nat Commun. 2022; 13(1): 5067.

[39] Wang M, Lei B, Zhu K, et al. Hard ferromagnetism in van der Waals Fe₃GaTe₂ nanoflake down to monolayer. npj 2D Mater Appl. 2024; 8(1):22.

[40] Jin W, Zhang G, Wu H, Yang L, Zhang W, Chang H. Room-temperature and tunable tunneling magnetoresistance in Fe₃GaTe₂-based 2D van der Waals heterojunctions. ACS Appl Mater Interfaces. 2023; 15(30): 36519-36526.

[41] Liu S, Hu S, Cui X, Kimura T. Efficient thermo-spin conversion in van der Waals ferromagnet FeGaTe. Adv Mater. 2024; 36(14):2309776.

[42] Kang S, Kim K, Kim BH, et al. Coherent many-body exciton in van der Waals antiferromagnet NiPS₃. Nature. 2020; 583(7818): 785-789.

[43] Kim SY, Kim TY, Sandilands LJ, et al. Charge-spin correlation in van der Waals antiferromagnet NiPS₃. Phys Rev Lett. 2018; 120(13):136402.

[44] Takubo K, Mizokawa T, Son JY, Nambu Y, Nakatsuji S, Maeno Y. Unusual superexchange pathways in an NiS₂ triangular lattice with negative charge-transfer energy. Phys Rev Lett. 2007; 99(3):037203.

[45] Wang X, Cao J, Lu Z, et al. Spin-induced linear polarization of photoluminescence in antiferromagnetic van der Waals crystals. Nat Mater. 2021; 20(7): 964-970.

[46] Chandrasekharan N, Vasudevan S. Magnetism and exchange in the layered antiferromagnet NiPS₃. J Phys Condens Matter. 1994; 6(24): 4569-4579.

[47] Xu Y, Zhang F, Fert A, et al. Orbitronics: light-induced orbital currents in Ni studied by terahertz emission experiments. Nat Commun. 2024; 15(1): 2043.

[48] Zhang G, Wu H, Yang L, et al. Above-room-temperature ferromagnetism regulation in two-dimensional heterostructures by van der Waals interfacial magnetochemistry. J Am Chem Soc. 2024; 146(49): 34070-34079.

[49] Kawamura T, Das Sarma S. Phonon-scattering-limited electron mobilities in AlxGa_1−xAs/GaAs heterojunctions. Phys Rev B. 1992; 45(7): 3612-3627.

[50] Olsen T. Magnetic anisotropy and exchange interactions of two-dimensional FePS₃, NiPS₃ and MnPS₃ from first principles calculations. J Phys D Appl Phys. 2021; 54(31):314001.

[51] Deng Y, Wang M, Xiang Z, et al. Room-temperature highly efficient nonvolatile magnetization switching by current in van der Waals Fe₃GaTe₂ devices. Nano Lett. 2024; 24(30): 9302-9310.

[52] Manipatruni S, Nikonov DE, Lin C-C, et al. Scalable energy-efficient magnetoelectric spin-orbit logic. Nature. 2019; 565(7737): 35-42.

[53] Mi M, Zheng X, Wang S, et al. Variation between antiferromagnetism and ferrimagnetism in NiPS₃ by electron doping. Adv Funct Mater. 2022; 32(29):2112750.

[54] Chen H, Xing Y, Wang X, et al. Electrical control of exchange bias in Fe₃GaTe₂/Fe₃GeTe₂ van der Waals heterostructures. Appl Phys Lett. 2025; 126(1):011901.

[55] Wu Q, Zhang Y, Cui Z, et al. Giant and nonvolatile control of exchange bias in Fe₃GeTe₂/irradiated Fe₃GeTe₂/MgO heterostructure through ultralow voltage. Adv Funct Mater. 2023; 33(23):2214007.

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