Magnetic phase crossover in strongly correlated EuMn2P2

TL;DR

This study reveals a magnetic phase crossover in EuMn2P2, where Mn magnetic correlations develop without long-range order, contrasting with related compounds, and highlights the sensitivity of electronic structure to magnetic configurations.

Contribution

It uncovers a magnetic phase crossover in EuMn2P2 and demonstrates the persistent Mn magnetic correlations despite the absence of long-range order, supported by experimental and theoretical analysis.

Findings

Mn magnetic correlations develop from 250-100 K

EuMn2P2 remains insulating without Mn long-range order

Band structure is highly sensitive to magnetic configurations

Abstract

Strong electron correlations underlie a plethora of electronic and magnetic components and devices and are often used to identify and probe novel ground states in quantum materials. Herein we report a magnetic phase crossover in EuMn2P2, an insulator which shows Eu antiferromagnetism at TN=17K, but no phase transition attributed to Mn magnetism. The absence of a Mn magnetic phase transition contrasts with the formation of long-range Mn order at T=130K in isoelectronic EuMn2Sb2 and EuMn2As2. Temperature-dependent specific heat and 31P NMR measurements provide evidence for the development of Mn magnetic correlations from T=250-100 K. Density functional theory calculations demonstrate an unusual sensitivity of the band structure to the details of the imposed Mn and Eu magnetic order, with antiferromagnetic Mn order required to recapitulate an insulating state. Our results imply a picture in which long range Mn magnetic order is suppressed by chemical pressure, but that magnetic correlations persist, narrowing bands and producing an insulating state.