Journal Home > Volume 15 , Issue 8

In recent years, few-layer or even monolayer ferromagnetic materials have drawn a great deal of attention due to the promising integration of two-dimensional (2D) magnets into next-generation spintronic devices. The SrRuO3 monolayer is a rare example of stable 2D magnetism under ambient conditions, but only weak ferromagnetism or antiferromagnetism has been found. The bi-atomic layer SrRuO3 as another environmentally inert 2D magnetic system has been paid less attention heretofore. Here we study both the bi-atomic layer and monolayer SrRuO3 in (SrRuO3)n/(SrTiO3)m (n = 1, 2) superlattices in which the SrTiO3 serves as a non-magnetic and insulating space layer. Although the monolayer exhibits arguably weak ferromagnetism, we find that the bi-atomic layer exhibits exceedingly strong ferromagnetism with a Tc of 125 K and a saturation magnetization of 1.2 µB/Ru, demonstrated by both superconducting quantum interference device (SQUID) magnetometry and element-specific X-ray circular dichroism. Moreover, in the bi-atomic layer SrRuO3, we demonstrate that random fluctuations and orbital reconstructions inevitably occurring in the 2D limit are critical to the electrical transport, but are much less critical to the ferromagnetism. Our study demonstrates that the bi-atomic layer SrRuO3 is an exceedingly strong 2D ferromagnetic oxide which has great potentials for applications of ultracompact spintronic devices.


menu
Abstract
Full text
Outline
Electronic supplementary material
About this article

The exceedingly strong two-dimensional ferromagnetism in bi-atomic layer SrRuO3 with a critical conduction transition

Show Author's information Jingxian Zhang1,§Long Cheng2,§( )Hui Cao3,§Mingrui Bao2Jiyin Zhao4Xuguang Liu4Aidi Zhao2Yongseong Choi5Hua Zhou5Padraic Shafer6Xiaofang Zhai2( )
Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
Instrument Center for Physical Science, University of Science and Technology of China, Hefei 230026, China
X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

§ Jingxian Zhang, Long Cheng, and Hui Cao contributed equally to this work.

Abstract

In recent years, few-layer or even monolayer ferromagnetic materials have drawn a great deal of attention due to the promising integration of two-dimensional (2D) magnets into next-generation spintronic devices. The SrRuO3 monolayer is a rare example of stable 2D magnetism under ambient conditions, but only weak ferromagnetism or antiferromagnetism has been found. The bi-atomic layer SrRuO3 as another environmentally inert 2D magnetic system has been paid less attention heretofore. Here we study both the bi-atomic layer and monolayer SrRuO3 in (SrRuO3)n/(SrTiO3)m (n = 1, 2) superlattices in which the SrTiO3 serves as a non-magnetic and insulating space layer. Although the monolayer exhibits arguably weak ferromagnetism, we find that the bi-atomic layer exhibits exceedingly strong ferromagnetism with a Tc of 125 K and a saturation magnetization of 1.2 µB/Ru, demonstrated by both superconducting quantum interference device (SQUID) magnetometry and element-specific X-ray circular dichroism. Moreover, in the bi-atomic layer SrRuO3, we demonstrate that random fluctuations and orbital reconstructions inevitably occurring in the 2D limit are critical to the electrical transport, but are much less critical to the ferromagnetism. Our study demonstrates that the bi-atomic layer SrRuO3 is an exceedingly strong 2D ferromagnetic oxide which has great potentials for applications of ultracompact spintronic devices.

Keywords: weak localization, two-dimensional (2D) ferromagnetism, correlated oxides, SrRuO3, non-Fermi liquid

References(37)

1

Gong, C.; Li, L.; Li, Z. L.; Ji, H. W.; Stern, A.; Xia, Y.; Cao, T.; Bao, W.; Wang, C. Z.; Wang, Y. A. et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. Nature 2017, 546, 265–269.

2

Huang, B.; Clark, G.; Navarro-Moratalla, E.; Klein, D. R.; Cheng, R.; Seyler, K. L.; Zhong, D.; Schmidgall, E.; McGuire, M. A.; Cobden, D. H. et al. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature 2017, 546, 270–273.

3

Gong, C.; Zhang, X. Two-dimensional magnetic crystals and emergent heterostructure devices. Science 2019, 363, eaav4450.

4

Zhang, S. Q.; Xu, R. Z.; Luo, N. N.; Zou, X. L. Two-dimensional magnetic materials: Structures, properties and external controls. Nanoscale 2021, 13, 1398–1424.

5

Liu, Z.; Deng, L. J.; Peng, B. Ferromagnetic and ferroelectric two-dimensional materials for memory application. Nano Res. 2021, 14, 1802–1813.

6

Klein, L.; Dodge, J. S.; Ahn, C. H.; Snyder, G. J.; Geballe, T. H.; Beasley, M. R.; Kapitulnik, A. Anomalous spin scattering effects in the badly metallic itinerant ferromagnet SrRuO3. Phys. Rev. Lett. 1996, 77, 2774–2777.

7
Xia, J. ; Siemons, W.; Koster, G.; Beasley, M. R.; Kapitulnik, A. Critical thickness for itinerant ferromagnetism in ultrathin films of SrRuO3. Phys. Rev. B 2009, 79, 140407(R).
8

Klein, L.; Dodge, J. S.; Geballe, T. H.; Kapitulnik, A.; Marshall, A. F.; Antognazza, L.; Char, K. Perpendicular magnetic anisotropy and strong magneto−optic properties of SrRuO3 epitaxial films. Appl. Phys. Lett. 1995, 66, 2427–2429.

9

Izumi, M.; Nakazawa, K.; Bando, Y. TC suppression of SrRuO3/SrTiO3 superlattices. J. Phys. Soc. Jpn. 1998, 67, 651–654.

10

Liu, Z. Q.; Ming, Y.; Lü, W. M.; Huang, Z.; Wang, X.; Zhang, B. M.; Li, C. J.; Gopinadhan, K.; Zeng, S. W.; Annadi, A. et al. Tailoring the electronic properties of SrRuO3 films in SrRuO3/LaAlO3 superlattices. Appl. Phys. Lett. 2012, 101, 223105.

11

Bern, F.; Ziese, M.; Setzer, A.; Pippel, E.; Hesse, D.; Vrejoiu, I. Structural, magnetic and electrical properties of SrRuO3 films and SrRuO3/SrTiO3 superlattices. J. Phys.: Condens. Matter 2013, 25, 496003.

12

Jeong, H.; Jeong, S. G.; Mohamed, A. Y.; Lee, M.; Noh, W. S.; Kim, Y.; Bae, J. S.; Choi, W. S.; Cho, D. Y. Thickness-dependent orbital hybridization in ultrathin SrRuO3 epitaxial films. Appl. Phys. Lett. 2019, 115, 092906.

13

Verissimo-Alves, M.; García-Fernández, P.; Bilc, D. I.; Ghosez, P.; Junquera, J. Highly confined spin-polarized two-dimensional electron gas in SrTiO3/SrRuO3 superlattices. Phys. Rev. Lett. 2012, 108, 107003.

14

Huang, A.; Hung, S. H.; Jeng, H. T. Strain induced metal-insulator transition of magnetic SrRuO3 single layer in SrRuO3/SrTiO3 superlattice. Appl. Sci. 2018, 8, 2151.

15

Cui, Z. Z.; Grutter, A. J.; Zhou, H.; Cao, H.; Dong, Y. Q.; Gilbert, D. A.; Wang, J. Y.; Liu, Y. S.; Ma, J. J.; Hu, Z. P. et al. Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer. Sci. Adv. 2020, 6, eaay0114.

16

Boschker, H.; Harada, T.; Asaba, T.; Ashoori, R.; Boris, A. V.; Hilgenkamp, H.; Hughes, C. R.; Holtz, M. E.; Li, L.; Muller, D. A. et al. Ferromagnetism and conductivity in atomically thin SrRuO3. Phys. Rev. X 2019, 9, 011027.

17

Mahadevan, P.; Aryasetiawan, F.; Janotti, A.; Sasaki, T. Evolution of the electronic structure of a ferromagnetic metal: Case of SrRuO3. Phys. Rev. B 2009, 80, 035106.

18
Si, L.; Zhong, Z. C.; Tomczak, J. M.; Held, K. Route to room-temperature ferromagnetic ultrathin SrRuO3 films. Phys. Rev. B 2015, 92, 041108(R).
19

Jeong, S. G.; Min, T.; Woo, S.; Kim, J.; Zhang, Y. Q.; Cho, S. W.; Son, J.; Kim, Y. M.; Han, J. H.; Park, S. et al. Phase instability amid dimensional crossover in artificial oxide crystal. Phys. Rev. Lett. 2020, 124, 026401.

20

Xie, X. C.; Das Sarma, S. Transition from one- to two-dimensional fluctuating variable-range-hopping conduction in microstructures. Phys. Rev. B 1987, 36, 4566–4569.

21

Tsigankov, D. N.; Efros, A. L. Variable range hopping in two-dimensional systems of interacting electrons. Phys. Rev. Lett. 2002, 88, 176602.

22

Lee, P. A.; Ramakrishnan, T. V. Disordered electronic systems. Rev. Mod. Phys. 1985, 57, 287–337.

23

Stewart, G. R. Non-Fermi-liquid behavior in d- and f-electron metals. Rev. Mod. Phys. 2001, 73, 797–855.

24

Miranda, E. Dobrosavljević, V. Disorder-driven non-Fermi liquid behaviour of correlated electrons. Rep. Prog. Phys. 2005, 68, 2337–2408.

25

Altshuler, B. L.; Aronov, A. G. Fermi-liquid theory of the electron-electron interaction effects in disordered metals. Solid State Commun. 1983, 46, 429–435.

26

Dwivedi, G. D.; Sun, S. J.; Kuo, Y. K.; Chou, H. Role of electron–magnon interaction in non-Fermi liquid behavior of SrRuO3. J. Phys.: Condens. Matter 2019, 31, 125602.

27

Allen, P. B.; Berger, H.; Chauvet, O.; Forro, L.; Jarlborg, T.; Junod, A.; Revaz, B.; Santi, G. Transport properties, thermodynamic properties, and electronic structure of SrRuO3. Phys. Rev. B 1996, 53, 4393–4398.

28

Meng, M.; Wang, Z.; Fathima, A.; Ghosh, S.; Saghayezhian, M.; Taylor, J.; Jin, R. Y.; Zhu, Y. M.; Pantelides, S. T.; Zhang, J. D. et al. Interface-induced magnetic polar metal phase in complex oxides. Nat. Commun. 2019, 10, 5248.

29

Jeong, S. G.; Han, G.; Song, S.; Min, T.; Mohamed, A. Y.; Park, S.; Lee, J.; Jeong, H. Y.; Kim, Y. M.; Cho, D. Y. et al. Propagation control of octahedral tilt in SrRuO3 via artificial heterostructuring. Adv. Sci. 2020, 7, 2001643.

30

Lee, H. G.; Wang, L. F.; Si, L.; He, X. Y.; Porter, D. G.; Kim, J. R.; Ko, E. K.; Kim, J.; Park, S. M.; Kim, B. et al. Atomic-scale metal-insulator transition in SrRuO3 ultrathin films triggered by surface termination conversion. Adv. Mater. 2020, 32, 1905815.

31

Agrestini, S.; Hu, Z.; Kuo, C. Y.; Haverkort, M. W.; Ko, K. T.; Hollmann, N.; Liu, Q.; Pellegrin, E.; Valvidares, M.; Herrero-Martin, J. et al. Electronic and spin states of SrRuO3 thin films: An X-ray magnetic circular dichroism study. Phys. Rev. B 2015, 91, 075127.

32

Chang, Y. J.; Kim, C. H.; Phark, S. H.; Kim, Y. S.; Yu, J.; Noh, T. W. Fundamental thickness limit of itinerant ferromagnetic SrRuO3 thin films. Phys. Rev. Lett. 2009, 103, 057201.

33

Kang, S.; Tseng, Y.; Kim, B. H.; Yun, S.; Sohn, B.; Kim, B.; McNally, D.; Paris, E.; Kim, C. H.; Kim, C. et al. Orbital-selective confinement effect of Ru 4d orbitals in SrRuO3 ultrathin film. Phys. Rev. B 2019, 99, 045113.

34

Toyota, D.; Ohkubo, I.; Kumigashira, H.; Oshima, M.; Ohnishi, T.; Lippmaa, M.; Kawasaki, M.; Koinuma, H. Ferromagnetism stabilization of ultrathin SrRuO3 films: Thickness-dependent physical properties. J. Appl. Phys. 2006, 99, 08N505.

35

Kourkoutis, L. F.; Song, J. H.; Hwang, H. Y.; Muller, D. A. Microscopic origins for stabilizing room-temperature ferromagnetism in ultrathin manganite layers. Proc. Natl. Acad. Sci. USA 2010, 107, 11682–11685.

36

Liao, Z. L.; Li, F. M.; Gao, P.; Li, L.; Guo, J. D.; Pan, X. Q.; Jin, R.; Plummer, E. W.; Zhang, J. D. Origin of the metal-insulator transition in ultrathin films of La2/3Sr1/3MnO3. Phys. Rev. B 2015, 92, 125123.

37

Wu, P. C.; Song, H. L.; Yuan, Y.; Feng, B.; Ikuhara, Y.; Huang, R.; Yu, P.; Duan, C. G.; Chu, Y. H. Thickness dependence of transport behaviors in SrRuO3/SrTiO3 superlattices. Phys. Rev. Mater. 2020, 4, 014401.

File
12274_2022_4392_MOESM1_ESM.pdf (467.8 KB)
Publication history
Copyright
Acknowledgements

Publication history

Received: 21 January 2022
Revised: 21 March 2022
Accepted: 05 April 2022
Published: 08 June 2022
Issue date: August 2022

Copyright

© Tsinghua University Press 2022

Acknowledgements

Acknowledgements

The work was supported by the National Natural Science Foundation of China (Nos. 52072244 and 12104305), the Science and Technology Commission of Shanghai Municipality (No. 21JC1405000), and the ShanghaiTech Startup Fund. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract (No. DE-AC02-06CH11357) and the Advanced Light Source, a U.S. DOE Office of Science User Facility under Contract (No. DE-AC02-05CH11231).

Return