# Observation of a new field-induced phase transition and its concomitant quantum critical fluctuations in CeCo(In$_{1-x}$Zn$_x$)$_5$

## TL;DR

This study reveals a new field-induced antiferromagnetic phase and associated quantum critical fluctuations in Zn-doped CeCoIn5, linking these phenomena to hidden order parameters and scaling behaviors similar to pure CeCoIn5.

## Contribution

It uncovers a new field-induced AFM phase and quantum critical fluctuations in Zn-doped CeCoIn5, connecting them to hidden order parameters and scaling laws.

## Key findings

- Field-induced AFM order appears at 5-10 T
- Specific heat shows -lnT dependence at B~10 T
- Scaling behavior of C_e/T matches ln[(B-B_0)/T^{2.7}]

## Abstract

We demonstrate a close connection between observed field-induced antiferromagnetic (AFM) order and quantum critical fluctuation (QCF) in the Zn7%-doped heavy-fermion superconductor CeCoIn5. Magnetization, specific heat, and electrical resistivity at low temperatures all show the presence of new field-induced AFM order under the magnetic field B of 5-10 T, whose order parameter is clearly distinguished from the low-field AFM phase observed for B < 5 T and the superconducting phase for B < 3 T. The 4f electronic specific heat divided by the temperature, C_e/T, exhibits -lnT dependence at B~10 T (= B_0), and furthermore, the C_e/T data for B >= B_0 are well scaled by the logarithmic function of B and T: ln[(B-B_0)/T^{2.7}]. These features are quite similar to the scaling behavior found in pure CeCoIn5, strongly suggesting that the field-induced QCF in pure CeCoIn5 originates from the hidden AFM order parameter equivalent to high-field AFM order in Zn7%-doped CeCoIn5.