Structure and Magnetism of c-plane Oriented Mn₅₀(Te_50-xSb_x) Epitaxial Thin Films with NiAs-type Structure

Abstract

  Structure, magnetism, and their correlation for NiAs-type Mn₅₀(Te_50-xSb_x) pseudo-single crystal films were investigated by changing the nearest Mn-Mn distance by substituting Te for Sb. The main results were as follows. First, c-plane oriented Mn₅₀(Te_50-xSb_x) pseudo-single crystal films were prepared in ranges of Sb composition, x, from 0 to 16 and from 33 to 51 by employing a c-plane oriented NiAs-type MnTe under-layer. Second, lattice parameter a of the Mn₅₀(Te_50-xSb_x) films was nearly constant at about 4.17 Å for 0 ≤ x ≤ 38 and reduced gradually down to 4.13 Å for x ≥ 38 as x increased. Lattice parameter c decreased with a gentle slope from 6.68 to 6.61 Å for 0 ≤ x ≤ 16 and reduced gradually down to 5.78 Å for x ≥ 23. As a result, d_Mn-Mn changed from 3.34 Å to 2.89 Å. Third, the saturation magnetic moments m_S at 5 K linearly increased with a different slope as x increased for 0 ≤ x ≤ 11 and 33 ≤ x ≤ 51. Finally, the coefficient of T ^3/2 in Bloch’s law A decreased rapidly for x ≤ 16 as x increased, and it increased gradually for 16 ≤ x ≤ 51 as x decreased.