Magnetic order, disorder, and excitations under pressure in the Mott insulator Sr$_2$IrO$_4$
| Autor: | A. de la Torre, Yejun Feng, Thomas Rosenbaum, R. S. Perry, D. M. Silevitch, David Hsieh, Anjana Krishnadas, Felix Baumberger, S. E. Cooper, Xiang Li |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Condensed Matter - Materials Science
Materials science Strongly Correlated Electrons (cond-mat.str-el) Condensed matter physics Magnetic order Mott insulator Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences ddc:500.2 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Condensed Matter - Strongly Correlated Electrons 0103 physical sciences Condensed Matter::Strongly Correlated Electrons 010306 general physics 0210 nano-technology |
| Zdroj: | Physical review. B., Vol. 104, No 20 (2021) P. L201111 |
| ISSN: | 2469-9950 |
| DOI: | 10.1103/PhysRevB.104.L201111 |
| Popis: | Protected by the interplay of on-site Coulomb interactions and spin-orbit coupling, Sr$_2$IrO$_4$ at high pressure is a rare example of a Mott insulator with a paramagnetic ground state. Here, using optical Raman scattering, we measure both the phonon and magnon evolution in Sr$_2$IrO$_4$ under pressure, and identify three different magnetically-ordered phases, culminating in a spin-disordered state beyond 18 GPa. A strong first-order structural phase transition drives the magnetic evolution at $\sim$10 GPa with reduced structural anisotropy in the IrO$_6$ cages, leading to increasingly isotropic exchange interactions between the Heisenberg spins and a spin-flip transition to $c$-axis-aligned antiferromagnetic order. In the disordered phase of Heisenberg $J_\mathrm{eff}=1/2$ pseudospins, the spin excitations are quasi-elastic and continuous to 10 meV, potentially hosting a gapless quantum spin liquid in Sr$_2$IrO$_4$. |
| Databáze: | OpenAIRE |
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