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arXiv · 2306.15450

Pressure-tuned quantum criticality in the large-$D$ antiferromagnet DTN

Kirill Yu. Povarov·David E. Graf·Andreas Hauspurg·Sergei Zherlitsyn·Joachim Wosnitza·Takahiro Sakurai·Hitoshi Ohta·Shojiro Kimura·Hiroyuki Nojiri·V. Ovidiu Garlea·Andrey Zheludev·Armando Paduan-Filho·Michael Nicklas·Sergei A. Zvyagin
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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.

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Kirill Yu. Povarov, David E. Graf, Andreas Hauspurg, Sergei Zherlitsyn, Joachim Wosnitza, Takahiro Sakurai, Hitoshi Ohta, Shojiro Kimura, Hiroyuki Nojiri, V. Ovidiu Garlea, Andrey Zheludev, Armando Paduan-Filho, Michael Nicklas, Sergei A. Zvyagin. 2023-06-27. Pressure-tuned quantum criticality in the large-$D$ antiferromagnet DTN. https://doi.org/10.1038/s41467-024-46527-x

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