1. Pressure-tuned quantum criticality in the large-$D$ antiferromagnet DTN
- Author
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Povarov, Kirill Yu., Graf, David E., Hauspurg, Andreas, Zherlitsyn, Sergei, Wosnitza, Joachim, Sakurai, Takahiro, Ohta, Hitoshi, Kimura, Shojiro, Nojiri, Hiroyuki, Garlea, V. Ovidiu, Zheludev, Andrey, Paduan-Filho, Armando, Nicklas, Michael, and Zvyagin, Sergei A.
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Condensed Matter - Strongly Correlated Electrons - Abstract
Strongly correlated spin systems can be driven to quantum critical points via various routes. In particular, gapped quantum antiferromagnets can undergo phase transitions into a magnetically ordered state with applied pressure or magnetic field, acting as tuning parameters. These transitions are characterized by $z=1$ or $z=2$ dynamical critical exponents, determined by the linear and quadratic low-energy dispersion of spin excitations, respectively. Employing high-frequency susceptibility and ultrasound techniques, we demonstrate that the tetragonal easy-plane quantum antiferromagnet NiCl$_{2}\cdot$4SC(NH$_2$)$_2$ (aka DTN) undergoes a spin-gap closure transition at about $4.2$ kbar, resulting in a pressure-induced magnetic ordering. The studies are complemented by high-pressure-electron spin-resonance measurements confirming the proposed scenario. Powder neutron diffraction measurements revealed that no lattice distortion occurs at this pressure and the high spin symmetry is preserved, establishing DTN as a perfect platform to investigate $z=1$ quantum critical phenomena. The experimental observations are supported by DMRG calculations, allowing us to quantitatively describe the pressure-driven evolution of critical fields and spin-Hamiltonian parameters in DTN., Comment: Main text: 9 pages, 7 figures. Supplemental Material: 8 pages, 6 figures
- Published
- 2023
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