Magnetic and thermal properties of the two-level magnetic system, KTm(MoO₄)₂

Abstract

The magnetic susceptibility and specific heat of single crystals of KTm(MoO4)2 in the temperature interval 0.1–300 K are investigated. It is shown that the ground state of the rare-earth magnetic system of the Tm3+ ions can be represented by two close-lying singlet levels (a non-Kramers quasidoublet with MJ = | +/- 6⟩) separated by a rather large energy interval from the excited levels. The effect of the ‘freezing’ of energy levels on magnetic susceptibility and the Schottky anomaly on magnetic specific heat have been observed in the low-temperature region T < 2.5 K. These results show that this magnetic system can be considered as a simple two-level quantum system over a wide temperature range.

Self-consistent approach for magnetic ordering and excited site occupation processes in a two-level system

“…It is hard to compare the theoretical results obtained here with the other ones due to the lack of an exact coincidence of our model with the one well-known in the literature. However, experimental investigations of magnetic phenomena induced by thermal or photo excited electrons in complex metal or metal-organic species are now intensively carried out [31][32][33][34]. Photo-induced magnetic structures based on the organic matrix intercalated by Rb and Cs atoms demonstrate thermodynamic properties above the Curie temperature close to the ones presented in figure 3 and figure 6.…”

Interaction of electronic excitations of Tm3+ions with acoustic vibrations in KTm(MoO4)2

“…1 Therefore structural phase transitions caused by the Jahn-Teller effect (including those induced by magnetic field) are quite frequent in these compounds. [2][3][4][5][6][7] In this paper, we discuss KTm(MoO 4 ) 2 for which previous measurements of the magnetic susceptibility and the specific heat have shown that neither structural phase transitions nor magnetic ordering occur down to 0.1 K. 8 The absence of the phase transitions may be caused by competition of magnetic and Jahn-Teller interactions of paramagnetic Tm 3+ ions. Such an effect has been observed in compounds of this family containing R 3+ ions with an even numbers of f electrons.…”

“…However, previous investigations on KTm(MoO 4 ) 2 revealed that the first Stark level is 2.3 cm −1 above the ground state; for the next level, this is 200 cm −1 . 8,11 Thus this compound can be considered to be an almost ideal quantum two-level system at low temperatures. It was shown that the low-energy quasidoublet formed by these levels have the maximum possible M J values: |M J = |± J = |±6 .…”