Abstract
In this paper, a temperature-induced valence-state transition is studied in a narrow composition range 0.2≤x≤ 0.375 of Ba2-xSrxTbIrO6 by means of x-ray and neutron powder diffraction, resonant inelastic x-ray scattering, magnetic susceptibility, electrical resistivity, and specific heat measurements. The valence-state transition involves an electron transfer between Tb and Ir leading to the valence-state change between Tb3+/Ir5+ and Tb4+/Ir4+ phases. This first-order transition has a dramatic effect on the lattice, transport properties, and the long-range magnetic order at low temperatures for both Tb and Ir ions. Ir5+ ion has an electronic configuration of 5d4 (Jeff=0), which is expected to be nonmagnetic. In contrast, Ir4+ ion with a configuration of 5d5(Jeff = 1/2) favors a long-range magnetic order. For x=0.1 with Tb3+/Ir5+ configuration to the lowest temperature (2 K) investigated in this paper, a spin-glass behavior is observed around 5 K indicating Ir5+ (Jeff=0) ions act as a spacer reducing the magnetic interactions between Tb3+ ions. For x=0.5 with Tb4+/Ir4+ configuration below the highest temperature 400 K of this paper, a long-range antiferromagnetic order at TN = 40 K is observed highlighting the importance of Ir4+ (Jeff = 1/2) ions in promoting the long-range magnetic order of both Tb and Ir ions. For 0.2 ≤x≤ 0.375, a temperature-induced valence-state transition from high-temperature Tb3+/Ir5+ phase to low-temperature Tb4+/Ir4+ phase occurs in the temperature range 180 K ≤T≤ 325 K and the transition temperature increases with x. The compositional dependence demonstrates the ability to tune the the valence state for a critical region of x that leads to a concurrent change in magnetism and structure. This tuning ability could be employed with suitable strain in thin films to act as a switch as the magnetism is manipulated.
| Original language | English |
|---|---|
| Article number | 054410 |
| Journal | Physical Review Materials |
| Volume | 6 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 2022 |
Funding
J.-Q.Y. would like to thank Nandini Trivedi, Patrick Woodward, and Jianshi Zhou for helpful discussions. Work at ORNL was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Synthesis of powder samples for neutron diffraction measurement and part of the manuscript preparation by Z.Y.Z. were supported by the National Natural Science Foundation of China (Grant No. 52072368). This research used resources at the High Flux Isotope Reactor, a DOE office of Science User Facility operated by the Oak Ridge National Laboratory. 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.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | |
| Office of Science | |
| Basic Energy Sciences | |
| Argonne National Laboratory | DE-AC02-06CH11357 |
| Division of Materials Sciences and Engineering | |
| National Natural Science Foundation of China | 52072368 |