Magnetic moment enhancement and spin polarization switch of the manganese phthalocyanine molecule on an IrMn(100) surface

Strain-induced magnetic moment enhancement in frustrated antiferromagnet Cs2CuBr4

The structure and magnetic properties are studied in co-doped Cs2-xKxCuBr4-xClxand pressurized Cs2CuBr4samples. No structural phase transition is found with doping concentrationx⩽ 0.1 and pre-compression pressure up to 4.5 GPa. The maximum susceptibility temperatureTmaxof the zero-field-cooling (ZFC) susceptibility curves decreases slightly with increasing doping concentration and pre-compression pressure, indicating only small changes in the exchange coupling constants. However, an unusual enhancement of the magnetic moment deduced from the ZFC susceptibility is observed in both series samples. A maximum increase of 40% is obtained in Cs1.9K0.1CuBr3.9Cl0.1sample. The magnetic moment increases almost linearly with decreasing Δ, i.e., defined as the wavenumber difference between the short- and long-bond stretching modes of the CuBr42-tetrahedra in the Raman spectra. The effect is likely due to the recovery of the Cu-3d orbital magnetic moments by strain-induced suppression of Jahn-Teller distortion in CuBr42-tetrahedra.

Grain-boundary segregation of 3d-transition metal solutes in bcc Fe: ab initio local-energy and d-electron behavior analysis

We present ab initio calculations of grain-boundary (GB) segregation of the series of 3d transition-metal (TM) solutes in bcc Fe, taking advantage of the local-energy analysis. For [Formula: see text]11(3 3 2) and [Formula: see text]3(1 1 1) [Formula: see text] symmetrical tilt GBs, the segregation behaviors of 3d-TM solutes can be classified into three groups. The early TMs (Sc, Ti and V) are preferentially segregated to the looser sites of GBs antiferromagnetically, the late TMs (Co, Ni and Cu) are preferentially segregated to the tighter sites of GBs ferromagnetically, and the middle TMs (Cr and Mn) are segregated antiferromagnetically without fixed site preference. TMs at both ends of the 3d series show larger segregation-energy gains, while Mn shows a cusp at the center, which is similar to the ab initio interaction energies between the 3d-TM solutes and a screw-dislocation core in bcc Fe. By the local-energy analysis combined with the local densities of states, the segregation of the early TMs is mainly attributed to the stabilization of surrounding Fe atoms by the TM solute at the looser sites of GBs, and that of the late TMs is mainly attributed to the stabilization of the TM solute itself from bulk Fe to GB sites and the destabilization of Fe atoms around the TM solute in bulk Fe. The cusp at Mn is mainly caused by the destabilization of Fe atoms around the Mn solute in bulk Fe, due to nearly-localized high-spin d states of Mn, in contrast to substantial d-d hybridization for Mn in GBs. For each group of 3d-TM solutes, the effects on the magnetic and mechanical properties of Fe GBs are also analyzed by the d-electron behavior in common with the segregation mechanism.

Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe(4)N interface. Fe(4)N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C p(z) and the out-of-plane d orbitals of Fe atom.