155Gd Mössbauer effect and magnetic properties of novel RT2B2C compounds with TNi, Co

\u3cp\u3eWe have prepared the compounds GdNi\u3csub\u3e2\u3c/sub\u3eB\u3csub\u3e2\u3c/sub\u3eC and GdCo\u3csub\u3e2\u3c/sub\u3eB\u3csub\u3e2\u3c/sub\u3eC and investigated their magnetic properties by means of \u3csup\u3e155\u3c/sup\u3eGd Mössbauer spectroscopy. From the temperature dependence of the hyperfine field, we derived that these two compounds give rise to magnetic ordering at 5.5±0.5 K and 21±1 K respectively. Large values of the electric field gradient V\u3csub\u3ezz\u3c/sub\u3e were found, reminiscent of compounds of the related ThCr\u3csub\u3e2\u3c/sub\u3eSi\u3csub\u3e2\u3c/sub\u3e type. A quantitative explanation of the origin of these field gradients is presented by ab initio band structure calculations. The experimental values of V\u3csub\u3ezz\u3c/sub\u3e have been used to estimate values for the second-order crystal field parameter in GdNi\u3csub\u3e2\u3c/sub\u3eB\u3csub\u3e2\u3c/sub\u3eC (A\u3csub\u3e2\u3c/sub\u3e \u3csup\u3e0\u3c/sup\u3e=-428Ka\u3csub\u3e0\u3c/sub\u3e \u3csup\u3e-2\u3c/sup\u3e) and GdCo\u3csub\u3e2\u3c/sub\u3eB\u3csub\u3e2\u3c/sub\u3eC (A\u3csub\u3e2\u3c/sub\u3e \u3csup\u3e0\u3c/sup\u3e=-346Ka\u3csub\u3e0\u3c/sub\u3e \u3csup\u3e-2\u3c/sup\u3e).\u3c/p\u3

Spin-dependent transport properties of Fe3O4/MoS2/Fe3O4 junctions

Magnetite is a half-metal with a high Curie temperature of 858 K, making it a promising candidate for magnetic tunnel junctions (MTJs). Yet, initial efforts to exploit its half metallic nature in Fe3O4/ MgO/Fe3O4 MTJ structures have been far from promising. Finding suitable barrier layer materials, which keep the half metallic nature of Fe3O4 at the interface between Fe3O4 layers and barrier layer, is one of main challenges in this field. Two-dimensional (2D) materials may be good candidates for this purpose. Molybdenum disulfide (MoS2) is a transition metal dichalcogenide (TMD) semiconductor with distinctive electronic, optical, and catalytic properties. Here, we show based on the first principle calculations that Fe3O4 keeps a nearly fully spin polarized electron band at the interface between MoS2 and Fe3O4. We also present the first attempt to fabricate the Fe3O4/MoS2/Fe3O4 MTJs. A clear tunneling magnetoresistance (TMR) signal was observed below 200 K. Thus, our experimental and theoretical studies indicate that MoS2 can be a good barrier material for Fe3O4 based MTJs.Our calculations also indicate that junctions incorporating monolayer or bilayer MoS2 are metallic