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Brar J, Bindu R. Investigation of magnetic exchange interactions in Cr-dopedCa0.5Sr0.5RuO3. J Phys Condens Matter 2024; 36:325503. [PMID: 38653327 DOI: 10.1088/1361-648x/ad4248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/23/2024] [Indexed: 04/25/2024]
Abstract
The value of Curie temperature (TC) and resistivity forCa0.5Sr0.5Ru1-xCrxO3are found to increase with increase inxfrom 0 to 0.1. TheTCincreases from 38 K to 107 K. In this work, we investigate the increment using spin polarised density functional theory. The compounds exhibit Griffiths phase. Our results show that to understand the behaviour of the increase inTC, it is important to consider not only the competing super exchange and super-super exchange interactions between Ru/Cr-Ru/Cr ion pairs but also the increment in the value of the magnetic moment due to the localized character of the dopant (Cr) ion. Our results suggest that the increased resistivity with Cr doping could be due to increased scattering rate and strong on-site coulomb repulsion due to Cr doping. It is also important to note that the behaviour ofTCwith the Ru-O-Ru bond angle is not in line with the functional form reported for ferrites, chromites and some ferromagnetic oxides. We believe that our results will be helpful in further exploring the origin of magnetism and transport on Cr doping in perovskite ruthenates.
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Affiliation(s)
- Jaskirat Brar
- School of Physical Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh 175005, India
| | - R Bindu
- School of Physical Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh 175005, India
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Kim D, Kim Y, Sohn B, Kim M, Kim B, Noh TW, Kim C. Electric Control of 2D Van Hove Singularity in Oxide Ultra-Thin Films. Adv Mater 2023; 35:e2207188. [PMID: 36764325 DOI: 10.1002/adma.202207188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/02/2023] [Indexed: 05/17/2023]
Abstract
Divergent density of states (DOS) can induce extraordinary phenomena such as significant enhancement of superconductivity and unexpected phase transitions. Moreover, van Hove singularities (VHSs) lead to divergent DOS in 2D systems. Despite recent interest in VHSs, only a few controllable cases have been reported to date. In this work, by utilizing an atomically ultra-thin SrRuO3 film, the electronic structure of a 2D VHS is investigated with angle-resolved photoemission spectroscopy and transport properties are controlled. By applying electric fields with alkali metal deposition and ionic-liquid gating methods, the 2D VHS and the sign of the charge carrier are precisely controlled. Use of a tunable 2D VHS in an atomically flat oxide film could serve as a new strategy to realize infinite DOS near the Fermi level, thereby allowing efficient tuning of electric properties.
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Affiliation(s)
- Donghan Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Younsik Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Byungmin Sohn
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Minsoo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Bongju Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
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Brar J, Singh S, Kuga K, Sharma P, M B, Takeuchi T, Bindu R. Lattice effects on the physical properties of half-doped perovskite ruthenates. J Phys Condens Matter 2023; 35:195402. [PMID: 36867880 DOI: 10.1088/1361-648x/acc15d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 03/03/2023] [Indexed: 06/18/2023]
Abstract
We investigate the unusual phase transitions in SrRuO3and Sr0.5Ca0.5Ru1-xCrxO3(x = 0, 0.05 and 0.1) employing x-ray diffraction, resistivity, magnetic studies and x-ray photoemission spectroscopy. Our results show the compounds undergo a crossover from itinerant ferromagnetism to localized ferromagnetism. The combined studies suggest Ru and Cr be in the 4+ valence state. A Griffith phase and an enhancement in Curie temperature (Tc) from 38 K to 107 K are observed with Cr doping. A shift in the chemical potential towards the valence band is observed with Cr doping. In the metallic samples, interestingly, a direct link between the resistivity and orthorhombic strain is observed. We also observe a connection between orthorhombic strain andTcin all the samples. Detailed studies in this direction will be helpful to choose suitable substrate materials for thin-film/device fabrication and hence manoeuvre its properties. In the non-metallic samples, the resistivity is mainly governed due to disorder, electron-electron correlation effects and a reduction in the number of electrons at the Fermi level. The value of the resistivity for the 5% Cr doped sample suggests semi-metallic behaviour. Understanding its nature in detail using electron spectroscopic techniques could unravel the possibility of its utility in high-mobility transistors at room temperature and its combined property with ferromagnetism will be helpful in making spintronic devices.
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Affiliation(s)
- Jaskirat Brar
- School of Physical Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh 175005, India
| | - Saurabh Singh
- Toyota Technological Institute, Nagoya, Aichi 468-8511, Japan
- Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Kentaro Kuga
- Toyota Technological Institute, Nagoya, Aichi 468-8511, Japan
- Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Priyamedha Sharma
- School of Physical Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh 175005, India
| | - Bharath M
- School of Physical Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh 175005, India
| | - Tsunehiro Takeuchi
- Toyota Technological Institute, Nagoya, Aichi 468-8511, Japan
- Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - R Bindu
- School of Physical Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh 175005, India
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Marković I, Watson MD, Clark OJ, Mazzola F, Abarca Morales E, Hooley CA, Rosner H, Polley CM, Balasubramanian T, Mukherjee S, Kikugawa N, Sokolov DA, Mackenzie AP, King PDC. Electronically driven spin-reorientation transition of the correlated polar metal Ca 3Ru 2O 7. Proc Natl Acad Sci U S A 2020; 117:15524-9. [PMID: 32576687 DOI: 10.1073/pnas.2003671117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The interplay between spin-orbit coupling and structural inversion symmetry breaking in solids has generated much interest due to the nontrivial spin and magnetic textures which can result. Such studies are typically focused on systems where large atomic number elements lead to strong spin-orbit coupling, in turn rendering electronic correlations weak. In contrast, here we investigate the temperature-dependent electronic structure of [Formula: see text], a [Formula: see text] oxide metal for which both correlations and spin-orbit coupling are pronounced and in which octahedral tilts and rotations combine to mediate both global and local inversion symmetry-breaking polar distortions. Our angle-resolved photoemission measurements reveal the destruction of a large hole-like Fermi surface upon cooling through a coupled structural and spin-reorientation transition at 48 K, accompanied by a sudden onset of quasiparticle coherence. We demonstrate how these result from band hybridization mediated by a hidden Rashba-type spin-orbit coupling. This is enabled by the bulk structural distortions and unlocked when the spin reorients perpendicular to the local symmetry-breaking potential at the Ru sites. We argue that the electronic energy gain associated with the band hybridization is actually the key driver for the phase transition, reflecting a delicate interplay between spin-orbit coupling and strong electronic correlations and revealing a route to control magnetic ordering in solids.
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