Synthesis, magnetization and magneto transport study of RECoPO (RE = La, Nd & Sm)

TL;DR

This study investigates the structural, magnetic, and magneto-transport properties of RECoPO compounds (RE = La, Nd, Sm), revealing complex magnetic transitions and interactions between 4f and 3d electrons in these layered materials.

Contribution

It provides new insights into the magnetic phase transitions and electron interactions in RECoPO compounds, especially the field and temperature dependence of FM and AFM states.

Findings

NdCoPO and SmCoPO exhibit successive PM-FM-AFM transitions.

Magneto-transport properties follow magnetic phase transitions.

Interaction between 4f and 3d electrons in Sm/NdCoPO is observed.

Abstract

We report the electrical, magneto transport and specific heat of the layered polycrystalline RECoPO (RE = La, Nd and Sm) samples. These compounds are iso-structural to recently discovered superconductor LaFeAs(O/F). Bulk polycrystalline samples are synthesized by solid state reaction route in an evacuated sealed quartz tube. All these compounds are crystallized in a tetragonal structure with space group P4/nmm. The Cobalt in these compounds is in itinerant state with its paramagnetic moment above 1.4\muB and the same orders ferromagnetically (FM) with saturation moment of around 0.20\muB below say 80K. Though, LaCoPO shows single paramagnetic (PM) to ferromagnetic (FM) transition near 35K, the NdCoPO and SmCoPO exhibit successive PM-FM-AFM transitions. Both FM and AFM transition temperatures vary with applied field. Although the itinerant ferromagnetism occurs with small saturation moment, typical anti-ferromagnetic (AFM) transitions (TN1, TN2) are observed at 69K and 14K for Nd and 57K and 45K for Sm. This FM-AFM transition of Co spins in NdCoPO and SmCoPO is both field and temperature dependent. The Magneto-transport of NdCoPO and SmCoPO distinctly follows their successive PM-FM-AFM transitions. It is clear that Sm/Nd (4f) interacts with the Co (3d) in first time synthesized Sm/NdCoPO.