# Quantum criticality of the Ising-like screw chain antiferromagnet SrCo2V2O8 in a transverse magnetic field

## TL;DR

This study investigates quantum critical points in the Ising-like screw chain antiferromagnet SrCo2V2O8 under a transverse magnetic field, revealing two critical points with distinct excitation properties through ultra-low temperature NMR and numerical analysis.

## Contribution

It identifies and characterizes two quantum critical points in SrCo2V2O8, highlighting the role of an effective staggered transverse field and the universality class of the second QCP.

## Key findings

- A QCP at approximately 7.0 T suppresses the Néel order.
- A second QCP at approximately 7.7 T exhibits gapless excitations.
- Numerical calculations support the universality of the second QCP.

## Abstract

The quantum criticality of an Ising-like screw chain antiferromagnet SrCo$_2$V$_2$O$_8$, with a transverse magnetic field applied along the crystalline $a$-axis, is investigated by ultra-low temperature NMR measurements. The N\'{e}el temperature is rapidly and continuously suppressed by the field, giving rise to a quantum critical point (QCP) at $H_{C{_1}}$$\approx$~7.0~T. Surprisingly, a second QCP at $H_{C{_2}}\approx$~7.7~T featured with gapless excitations is resolved from both the double-peak structure of the field dependent spin-lattice relaxation rate $1/^{51}T_1$ at low temperatures and the weakly temperature-dependent $1/^{51}T_1$ at this field. Our data, combined with numerical calculations, suggest that the induced effective staggered transverse field significantly lowers the critical fields, and leads to an exposed QCP at $H_{C{_2}}$, which belongs to the one-dimensional transverse-field Ising universality.