Physico-Chemical nanomaterials science

Electronic and magnetic properties of SmCo0.5Cr0.5O3
Shved V.M., Hreb V.M., Vasylechko L.O.
Lviv Polytechnic National University, Bandera Street, 12, Lviv-79013, Ukraine 
E-mail: shvedvira@gmail.com

The recent investigations of multiferroicity in the rare earth chromites RCrO3 have attracted a lot of interest to these compounds. The rare earth cobaltites RCoO3 are famous for the spin crossover and the magnetic features highly depended on spin state transitions. In this work, we used the first principles calculations to obtain the electronic and magnetic properties of mixed samarium cobaltite–chromite SmCo0.5Cr0.5O3 by means of ABINIT software package. The lattice constants and atomic coordinates of orthorhombic SmCo0.5Cr0.5O3 obtained from X-ray synchrotron diffraction measurements were used for the calculations. For an adequate description of highly localized 3d and 4f electrons, the hybrid exchange-correlation functional PBE0 was adopted. 
In SmCo0.5Cr0.5O3 the calculated band gap is 1.29 eV, the conduction band minimum is located at Г point and the valence band maximum occurs at S point. The bottom of the conduction band is generally derived from Co d, Cr d and O p states. The top of the valence band originates from hybridized Cr d and Co d states.
At low temperatures SmCoO3 is a non-magnetic material with a low spin state of Co3+ ions [1]. In contrast to SmCoO3, SmCrO3 exhibits the canted G-type antiferromagnetic ordering below Neel temperature (197 K) [2]. According to our calculations of the total ground state energy, the antiferromagnetic configuration has the lowest energy and is the most stable in SmCo0.5Cr0.5O3. The calculated local magnetic moment of Co3+ in SmCo0.5Cr0.5O3 is insignificant, proving that Co3+ ions are in the low spin state, similar to the parent SmCoO3 material [1]. The calculated magnetic moment per Cr3+ ion is 2.56 μB, which agrees well with the theoretical value of 2.798 μB obtained for the “pure” SmCrO3 chromite in Ref. [3]. The antiferromagnetic properties of SmCo0.5Cr0.5O3 can be explained mainly by the magnetic interactions of Cr3+ ions.

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