| Title: |
Magnetic order, disorder, and excitations under pressure in the Mott insulator Sr$_2$IrO$_4$ |
| Authors: |
Li, Xiang, Cooper, S. E., Krishnadas, A., de la Torre, A., Perry, R. S., Baumberger, F., Silevitch, D. M., Hsieh, D., Rosenbaum, T. F., Feng, Yejun |
| Source: |
Physical Review B 114, L201111 (2021) |
| Publication Year: |
2021 |
| Collection: |
Condensed Matter |
| Subject Terms: |
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science |
| More Details: |
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$_4$. |
| Document Type: |
Working Paper |
| DOI: |
10.1103/PhysRevB.104.L201111 |
| Access URL: |
http://arxiv.org/abs/2110.11588 |
| Accession Number: |
edsarx.2110.11588 |
| Database: |
arXiv |
