Magnetic Frustration on a Kagom\'{e} Lattice in R$\_{3}$Ga$\_{5}$SiO$\_{14}$ Langasites with R = Nd, Pr

TL;DR

This study investigates magnetic frustration in R3Ga5SiO14 langasites with R = Nd, Pr, revealing persistent disordered phases due to geometric frustration on a kagomé lattice despite antiferromagnetic interactions.

Contribution

It provides experimental evidence of magnetic frustration in rare earth langasites and models the magnetic moments as coplanar elliptic rotators, highlighting the complex magnetic behavior.

Findings

Disordered magnetic phase persists down to very low temperatures.

Magnetic moments behave as coplanar elliptic rotators.

Antiferromagnetic interactions are present but do not lead to magnetic order.

Abstract

In the R$\_{3}$Ga$\_{5}$SiO$\_{14}$ compounds, the network R of rare earth cations form well separated planes of corner sharing triangles topologically equivalent to a kagom\'e lattice. Powder samples and single crystals with R = Nd and Pr were prepared and magnetostatic measurements were performed under magnetic field up to 10 T in the temperature range from 1.6 K to 400 K. Analysis of the magnetic susceptibility at the high temperatures where only the quadrupolar term of the crystal electric field prevails, suggests that the Nd and Pr magnetic moments can be modeled as coplanar elliptic rotators perpendicular to the three fold axis of the crystal structure that interact antiferromagnetically. Nonetheless, a disordered phase that can be ascribed to geometric frustration persists down to the lowest temperature which is about 25 times smaller than the energy scale for the exchange interactions.