Evidence for pressure induced unconventional quantum criticality in the coupled spin ladder antiferromagnet C${}_9$H${}_{18}$N${}_2$CuBr${}_4$

Abstract

Quantum phase transitions in quantum matter occur at zero temperature between distinct ground states by tuning a nonthermal control parameter. Often, they can be accurately described within the Landau theory of phase transitions, similarly to conventional thermal phase transitions. However, this picture can break down under certain circumstances. Here, we present a comprehensive study of the effect of hydrostatic pressure on the magnetic structure and spin dynamics of the spin-1/2 ladder compound C${}_9$H${}_{18}$N${}_2$CuBr${}_4$. Single-crystal heat capacity and neutron diffraction measurements reveal that the N$\acute{\mathrm{e}}$el-ordered phase breaks down beyond a critical pressure of $P_{\mathrm{c}}$$\sim$1.0 GPa through a continuous quantum phase transition. Estimates of the critical exponents suggest that this transition may fall outside the traditional Landau paradigm. The inelastic neutron scattering spectra at 1.3 GPa are characterized by two well-separated gapped modes, including one continuum-like and another resolution-limited excitation in distinct scattering channels, which further indicates an exotic quantum-disordered phase above $P_{\mathrm{c}}$.

The revised version includes 10 pages and 5 figures in the main text. To appear in Nature Communications. Any comments are welcome

References in corpus (21)

• "Deconfined" quantum critical points
• Quantum criticality beyond the Landau-Ginzburg-Wilson paradigm
• Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions
• Spontaneous Magnon Decays
• Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3
• Generalized Directed Loop Method for Quantum Monte Carlo Simulations
• Scaling in the Fan of an Unconventional Quantum Critical Point
• Quantum and classical criticality in a dimerized quantum antiferromagnet
• The Cold Neutron Chopper Spectrometer at the Spallation Neutron Source - A Review of the first 8 Years of Operation
• Deconfined quantum critical point in one dimension
• Spin liquid phase in a $S=1/2$ quantum magnet on the kagome lattice
• Direct observation of the Higgs amplitude mode in a two-dimensional quantum antiferromagnet near the quantum critical point
• Anisotropy of Magnetic Interactions in the Spin-Ladder Compound (C${}_5$H${}_{12}$N)${}_2$CuBr${}_4$
• Effect of pressure on the quantum spin ladder material IPA-CuCl3
• Magnetic ordering induced by interladder coupling in the spin-1/2 Heisenberg two-leg ladder antiferromagnet C${}_9$H${}_{18}$N${}_2$CuBr${}_4$
• Decay and renormalization of a longitudinal mode in a quasi-two-dimensional antiferromagnet
• Continuous phase transition between Neel and valence bond solid phases in a J-Q-like spin ladder system
• Neutron scattering study of a quasi-2D spin-1/2 dimer system Piperazinium Hexachlorodicuprate under hydrostatic pressure
• The Higgs Mode of Planar Coupled Spin-Ladders and its Observation in C${}_9$H${}_{18}$N${}_2$CuBr${}_4$
• Stable Higgs mode in anisotropic quantum magnets
• Anisotropy-induced soliton excitation in magnetized strong-rung spin ladders

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• Deconfined quantum criticality on a triangular Rydberg array
• Zr-based bulk metallic glass clamp cell for high-pressure inelastic neutron scattering