Physical properties of new delafossite triangular-lattice compounds TlErSe$_2$ and TlTmSe$_2$

Bastian Rubrecht; Ellen Häußler; Mirtha Pillaca; Pritam Bhattacharyya; Liviu Hozoi; Artem Nosenko; Dmitri V. Efremov; Bernd Büchner; Anja U. B. Wolter; Thomas Doert

Paper

Physical properties of new delafossite triangular-lattice compounds TlErSe$_2$ and TlTmSe$_2$

Abstract

Delafossite compounds containing rare-earth ions have been proven to be an ideal platform to investigate frustrated magnetic ground states. Here, we discuss two triangular-lattice antiferromagnets, TlErSe

and TlTmSe

, as potential candidates for hosting exotic quantum states. Powder X-ray diffraction data analysis of the black-color polycrystalline Tl

(

: Er and Tm) samples confirms the phase purity. Both materials crystallize in the trigonal

-NaFeO

structure (

) with lattice parameters

= 4.1070(4) Å and

= 23.1472(1) Å for the erbium compound and

= 4.0916(1) Å and

= 23.1483(2) Å for the thulium compound. Magnetic susceptibility measurements show an effective moment of

/f.u. (

/f.u.) for TlErSe

(TlTmSe

) for temperatures above 200 K. While

He specific-heat measurements reveal long-range magnetic order below

K for TlErSe

, no sign of long-range magnetic order was observed for TlTmSe

. Based on our results, we map out the T-H phase diagram for polycrystalline TlErSe

and discuss the striking difference in the magnetic behavior of TlTmSe

based on our ab initio quantum chemical calculations.