Electronic and Magnetic Properties of ThCo₄B

Abstract

ThCo 4 B compound crystallizes in the hexagonal CeCo 4 B type structure. The electronic structure is calculated based on full-potential local--orbital full-relativistic method. The ab initio calculations showed that small magnetic moments (≈ 0.1 µB/atom) are formed on Th and B atoms, antiparallel to the moments on Co atoms equal to 1.55 and 0.43 µ B /atom for Co(2c) and Co(6i), respectively. The densities of states at the Fermi level are equal to 1.3 and 5.4 states/(eV spin f.u.) for spin up and down, respectively. These values are predominated by Co(3d) electrons. IntroductionRecently uranium compounds have attracted interest because of many interesting properties such as the Pauli paramagnetism, spin fluctuations, heavy fermions, magnetic ordering, or superconductivity [1,2]. Wide range of properties in these compounds is caused by the uranium 5f electrons, which show an intermediate character between the localized 4f electron system and itinerant character of 3d electrons. The role of 5f electrons is important in actinides and the question is if they are localized or itinerant or perhaps the two situations coexist giving rise to a new character of the electronic structure, referred to as the duality of the behavior of 5f electrons [3]. It is very useful to compare properties of isostructural systems with and without 5f electrons treating the systems with thorium as reference ones. The ThCo 4 B phase crystallizes in a hexagonal CeCo 4 B type structure and orders ferromagnetically at 303 K [4]. Investigations by high resolution neutron diffraction gave magnetic moments on Co atoms equal to 1.2 and 0.2 µ B /atom for 2c and 6i site, respectively [4]. In isostructural UCo 4 B no magnetic order was observed [5].The aim of this paper is to calculate electronic structure of the ThCo 4 B compound based on a spin-polarized ab initio method.

Magnetic Properties and Electronic Structure of ThCo<sub>4</sub>B

“…The splitting into 6 p1/2 and 6 p3/2 is around 7 eV however it is a bit larger for the Th (1a) atom. Our calculation is consistent with the work of Szajek [24].…”

“…It is also evident that the magnetic moments at the non-equivalent Th (1a) and Th (1b) sites and at the B (2d) site are rather small and negative in good agreement with earlier work [17,24].The spin and site-resolved DOS for ThCo 4 B and ThCo 5 structures are shown in Figures 2(a) and (b) respectively. The main features of Figure 2 are:…”

Structural, magnetic and magnetocaloric effect of pyrochlore iridate Er2Ir2O7

“…Pyrochlore iridates of formula A 2 B 2 O 7 (A= rare Earth elements; and B= Ir) are one of the materials with a significant magnetic frustration owing to Coulomb correlation and spin-orbit coupling [25][26][27]. Among these materials we find: Pr 2 Ir 2 O 7 , Tb 2 Ir 2 O 7 , Eu 2 Ir 2 O 7 , Y 2 Ir 2−x Cr x O 7 [28][29][30], etc According to the findings on these materials, the lanthanides A and their interactions with the moments B = Ir frequently result in intriguing physical properties. These materials have been used in a variety of applications, including magnetic refrigeration.…”