Die magnetischen Eigenschaften der Alkalimetall-Manganpnictide KMnP, RbMnP, CsMnP, RbMnAs, KMnSb, KMnBi, RbMnBi und CsMnBi - Neutronenbeugungsuntersuchungen und Suszeptibilitätsmessungen

Large resistivity change and phase transition in the antiferromagnetic semiconductors LiMnAs and LaOMnAs

“…Regarding the non-Curie-Weiss-like behavior of the magnetization as a function of temperature reported for related AMnX compounds, 20 our DFT calculations (see below) have shown that within the layers, the Mn moments are very strongly coupled relative to the weak interlayer couplings. Additionally, in LiMnAs between the layers, the Mn atoms are actually coupled ferromagnetically with their next-nearest neighbors and antiferromagnetically with their second-nearest neighbors.…”

“…By combining ab initio density functional theory (DFT) calculations with our experiments, we discuss the electronic structure and magnetic exchange coupling of the Mn atoms, further commenting on the non-Curie-Weiss-like behavior experimentally reported for related compounds. 20 We will also comment on the issue arising from a previous work 9 regarding the weak ferromagnetic behavior observed in LaOMnAs, which was first attributed to a small spin canting 9 and in a later paper 21 explained via the formation of small amounts ( 1%) of MnAs as impurities during synthesis.…”

A useful pyramid scheme

“…These values, which can be used to estimate the Néel temperature T N , are larger in the I-Mn-V's than in metal Mn-based alloys whose T N ∼ 10 3 K. 15 Our calculations therefore reproduce not only the ground-state AFM structure of the I-Mn-V's but also explain the high T N observed in neutron-scattering experiments. [12][13][14] We also remark that our ab initio calculations show that the AFM ground state is comparably stable in the intrinsic material and in highly n-or p-type doped LiMnAs (we considered supercells corresponding to doping as high as ∼10 21 cm −3 ). All studied I-Mn-V compounds are intrinsic semiconductors for the stoichiometric composition 1:1:1 of the constituent elements; the band dispersions obtained within the localdensity approximation without and with correlation corrections (LDA and LDA + U) of LiMnAs and KMnAs are shown in Figs.…”

“…These experiments identified AFM coupling in the Mn planes persisting to very high temperatures and a weaker interlayer magnetic coupling that still persists in most of the I-Mn-V compounds above 400 K. [12][13][14] However, to the best of our knowledge, no experimental or theoretical report published to date has considered I-Mn-V compounds to be semiconductors, and no report has been published on epilayer growth of I-Mn-V's (or of any other compound with group-I alkali metals in the crystal structure).…”

“…The I-Mn-V compounds discussed in this paper combine the favorable tighter lattice arrangement of the group-V pnictides and the large magnetic moment on Mn, consistent with the observed high Néel temperatures in these materials. [12][13][14] The experimental investigation of epitaxial growth and characterization of LiMnAs layers is presented in Sec. II.…”