CePdAl - a Kondo lattice with partial frustration

Veronika Fritsch,Sarah Woitschach,Oliver Stockert,Christian Taubenheim,Philipp Gegenwart,Burkhard Schmidt,Hilbert V Löhneysen,Akito Sakai,Bjørn Pedersen,Kai Grube,Zita Huesges,Wolfram Kittler,Stefan Lucas

doi:10.1088/1742-6596/807/3/032003

Abstract

Magnetic frustration, which is well-defined in insulating systems with localized magnetic moments, yields exotic ground states like spin ices, spin glasses, or spin liquids. In metals magnetic frustration is less well defined because of the incipient delocalization of magnetic moments by the interaction with conduction electrons, viz., the Kondo effect. Hence, the Kondo effect and magnetic frustration are antithetic phenomena. Here we present experimental data of electrical resistivity, magnetization, specific heat and neutron diffraction on CePdAl, which is one of the rare examples of a geometrically frustrated Kondo lattice, demonstrating that the combination of Kondo effect and magnetic frustration leads to an unusual ground state.

Highlights

Geometric frustration can prevent magnetic ordering despite the presence of a sizable magnetic exchange interaction
Due to the Kondo effect local moments can be screened by the conduction electrons, leading to a non-magnetic ground state
Magnetic frustration and Kondo effect can in this respect be regarded as being antithetic: The Kondo effect, yielding a delocalization of the magnetic moments due to virtual transitions of 4f electrons to the Fermi level, is not beneficial for the formation of a frustrated state

Summary

Introduction

Geometric frustration can prevent magnetic ordering despite the presence of a sizable magnetic exchange interaction. In 4f -electron systems partial frustration is found in a few materials where one part of the magnetic moments forms long-range order, the other part remains disordered down to lowest temperature.

Results

Conclusion