Magnetic, optical, and magneto-optical properties of MnX(X=As, Sb, or Bi) from full-potential calculations

Abstract

The magneto-optic ͑MO͒ Kerr and Faraday spectra for manganese pnictides are calculated using the all electron, relativistic, full-potential linear muffin-tin orbital method. The amplitude of our calculated spectra are found to be in good agreement with corresponding experimental spectra. Although the MO property is a rather complicated function of the diagonal and off-diagonal elements of the optical conductivity tensor, present theory nevertheless provides very practical insight about its origin in these compounds. The largest Kerr effect observed in MnBi can be understood as a combined effect of maximal exchange splitting of Mn 3d states and the nearly maximal spin-orbit ͑s-o͒ coupling of Bi. The frequency-dependent optical properties, namely reflectivity, absorption coefficient, electron-energy-loss spectra, refractive index, extinction coefficient are given. From our calculations ͑including spin-orbit coupling and orbital polarization͒ the site-projected spin and orbital moments are also obtained and compared to the available experimental values and a good agreement is found. The magnetic anisotropy energy is calculated with a minimal number of approximations for the three systems. A disagreement between theory and experiment is found. Using the generalized gradient corrected fullpotential linear augmented plane-wave method we have calculated the unscreened plasma frequencies and the hyperfine parameters such as electric-field gradient as well as the hyperfine field. ͓S0163-1829͑99͒01419-8͔

Structure and magnetic properties of the MnBi low temperature phase

“…2, the magnetic moment of the Mn atom shows a small temperature dependence in the range from 10 to 300 K. The magnetic moment per Mn is 3.60 B and 4.18 B at room temperature and 10 K, which is well in agreement with the magnetic measurements on polycrystalline MnBi, 4,8 on single crystals, 15 and with theoretical band calculations. 17,18 The value at room temperature ͑RT͒ is considerably less than that obtained by previous neutron diffraction measurements, 7 where a value of 4.5 B was claimed at RT. Below 200 K, the magnetic moments of Mn deviate gradually from the direction parallel to the c axis and into the direction nearly perpendicular to the c axis at 50 K. A sharp increase of the angle between Mn magnetic moments and the c axis is observed around 90 K. However, the magnetic moment still shows a very small c-axis component at 10 K, i.e., it is not totally in the basal plane.…”

“…Additionally, recent band calculations with spin-orbital coupling and orbital polarization still result in disagreement between theoretical and experimental results. 18 Further studies regarding the temperature dependence of the anisotropy of MnBi are necessary.…”

Phase stability, electronic structure, and optical properties of indium oxide polytypes

“…The calculated optical parameters have more spectral structure [38][39][40][41] than what is commonly observed because no fluctuations are included. To facilitate comparison with experimental data, the calculated optical spectra is smoothed by broadening.…”

Half-Metallic Ferromagnetism and Structural Stability of Zincblende Phases of the Transition-Metal Chalcogenides

“…However, it is highly desirable to explore new halfmetallic ferromagnetic materials which are compatible with important III-V and II-VI semiconductors. For this purpose, effort has be made on the metastable zincblende (B3) phases such as the transition-metal pnictides [10,11,12,13,14,15,16,17,18,19,20]. Although zincblende phases of MnAs [11], CrAs [12,13] and CrSb [14] have been successfully fabricated as nanodots, ultrathin films and ultrathin layers in multilayers, it has not been possible to grow the zincblende half-metallic ferromagnetic phases as high-quality layers or thick films.…”