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Repeated uniform switching of the magnetization of thin films of ferrimagnetic amorphous Gdx(FeCo)1−x in response to single fast laser pulses is well established. Here, we report unusual toggle switching in thin films of sperimagnetic amorphous DyxCo1−x and TbxCo1−x with x ≈ 0.25 irradiated with single 200 fs pulses of 800 nm laser light. The samples have strong local random anisotropy due to the non-S state rare earth. The compensation temperature of the films is ≤180 K, and their Curie temperature is ≈500 K. They are largely switched by the first pulse, and subsequent pulses lead to partial re-switching of a decreasing amount of the irradiated area, with a granular structure of submicrometer regions of switched and unswitched material. Individual switched regions about 700 nm in size are observed around the edge of the irradiated spots where the fluence is at the threshold for switching. Results are discussed in terms of a random anisotropy model where the ratio of local anisotropy to exchange is temperature dependent.

Tunnel magnetoresistance ratios of up to 40% are measured between 10 K and 300 K when the highly spin-polarized compensated ferrimagnet, Mn2RuxGa, is integrated into MgO-based perpendicular magnetic tunnel junctions. Temperature and bias dependences of the tunnel magnetoresistance effect, with a sign change near −0.2 V, reflect the structure of the Mn2RuxGa interface density of states. Despite magnetic moment vanishing at a compensation temperature of 200 K for x≈0.8, the tunnel magnetoresistance ratio remains non-zero throughout the compensation region, demonstrating that the spin-transport is governed by one of the Mn sub-lattices only. Broad temperature range magnetic field immunity of at least 0.5 T is demonstrated in the same sample. The high spin polarization and perpendicular magnetic anisotropy make Mn2RuxGa suitable for applications in both non-volatile magnetic random access memory cells and terahertz spin-transfer oscillators.

Spin-dependent transport properties of Mn2RuxGa thin-films are studied as function of the Ru concentration and the substrate-induced strain. The large spontaneous Hall angle of 7.7% twenty times bigger than in other 3d metals is a signature of its half-metallicity. The compensation temperature where the magnetization of the two inequivalent antiferromagnetically coupled Mn sublattices cancel can be tuned by varying x or the biaxial strain. This zero-moment half metal is free from demagnetizing forces and creates no stray field, effectively removing two obstacles to integrating magnetic elements in densely packed, nanometer-scale memory elements, and millimeter-wave generators.

Oriented c-axis films of the hexagonal triangular antiferromagnetic e-Mn3Ga have been used in bottom-pinned synthetic antiferromagnet magnetic tunnel junctions with MgO barriers, which show up to 150% tunneling magnetoresistance at room temperature. Exchange bias fields as high as 150 mT can be achieved for samples field-cooled from 100 °C. Thin films of the antiferromagnet have a Neel temperature in excess of 650 K and provide an interface exchange energy with CoFe of 0.09 mJ m−2. They show an isotropic uncompensated magnetization of Ms = 48 kA m−1, with a coercivity μ0Hc > 3 T.

Oriented thin films of Mn3Ge with the tetragonal D022 structure, grown on strontium titanate substrates, exhibit a low magnetization Ms = 73 kA m−1 combined with high uniaxial anisotropy Ku = 0.91 MJ m−3 at 300 K, making them potentially useful for thermally stable sub-10 nm spin torque memory elements. The highly ordered epitaxial Mn3Ge (001) films show 46% diffusive spin polarization at the Fermi level, measured by point contact Andreev reflection. Density functional calculations show that the compounds are ferrimagnetic, with anisotropic spin polarization at the Fermi level.

The influence of contact materials on the electrical characteristics of field-effect transistors made from poly(3-hexylthiophene) with short-channel lengths of 80 nm is investigated. The thermally activated output current indicates the presence of a potential barrier at the electrode/organic contact. The barrier is not related to surface oxide and results in non-linear junction characteristics with activation voltage that can be only partially controlled via the work function of the contact metal. A Schottky contact at the metal/polymer interface arises from the band offset of the two materials and from interfacial dipole layers. Transistor operation with on/off ratio over 103 is achieved with five different electrode materials.

Equiatomic CoPt nanowires with a gold cap layer have been fabricated by electrochemical template synthesis. Au improves the structural and magnetic properties of the L10 ordered CoPt, leading to coercivities of up to 1.43 T. The anisotropy constant K1 was estimated as 3.9(9) MJ m−3 from the approach to saturation, and four effective anisotropy constants were determined from analysis of torque curves in a 14 T field. Multisegmented magnetic nanowires are produced using gold interlayers.