Abstract
The topotactic phase transition in SrCoO x (x = 2.5-3.0) makes it possible to reversibly transit between the two distinct phases, i.e. the brownmillerite SrCoO2.5 that is a roomerature antiferromagnetic insulator (AFM-I) and the perovskite SrCoO3 that is a ferromagnetic metal (FM-M), owing to their multiple valence states. For the intermediate x values, the two distinct phases are expected to strongly compete with each other. With oxidation of SrCoO2.5, however, it has been conjectured that the magnetic transition is decoupled to the electronic phase transition, i.e., the AFM-to-FM transition occurs before the insulator-to-metal transition (IMT), which is still controversial. Here, we bridge the gap between the two-phase transitions by density-functional theory calculations combined with optical spectroscopy. We confirm that the IMT actually occurs concomitantly with the FM transition near the oxygen content x = 2.75. Strong charge-spin coupling drives the concurrent IMT and AFM-to-FM transition, which fosters the near room-T magnetic transition characteristic. Ultimately, our study demonstrates that SrCoO x is an intriguingly rare candidate for inducing coupled magnetic and electronic transition via fast and reversible redox reactions.
Original language | English |
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Article number | 16066 |
Journal | Scientific Reports |
Volume | 7 |
Issue number | 1 |
DOIs | |
State | Published - Dec 1 2017 |
Funding
We appreciate valuable discussions with S. Okamoto. The work at UNIST (J.H.L., H.-J.L., J.H.S., J.N.) was supported by National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (2015R1C1A1A01055760), Basic Research Laboratory (NRF-2017R1A4A1015323), and Creative Materials Discovery Program through the NRF funded by the Ministry of Science and ICT(2017M3D1A1040828) (theoretical calculations). W.S.C., H.J., and H.N.L. were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (synthesis and experimental characterization). W.S.C. was in part supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF-2017R1A2B4011083) (optical data anaysis). Computation resources were supported by the Supercomputing Center/Korea Institute of Science and Technology Information with supercomputing resources including technical support (KSC-2017-C3-0018).