Single crystal studies and electronic structure investigation of a room-temperature semiconductor NaMnAs.

We report synthesis of single crystalline NaMnAs, confirm its antiferromagnetic order and characterise the sample by photoemission spectroscopy. The electronic structure was studied using optical transmittance, x-ray and ultraviolet spectroscopy and by theoretical modeling using local density approximation (LDA) extended to LDA+U when Heisenberg model parameters were determined. Optical transmittance measurement have confirmed the theoretical predictions that NaMnAs is a semiconductor. Also the Neel temperature was closer determined for the first time from temperature dependence of magnetization, in agreement with our Monte Carlo simulations.