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We present a theoretical investigation of the electronic and magnetic structure of spinel CdCr_2Te_4 using density functional theory, its extensions via onsite Hubbard U interactions, and a screened-hybrid-functional exchange potential. We find that the ground state is semiconducting within the latter approach, and within this magnetic-semiconducting system we compute the complex band structure, finding a slowly decaying evanescent $\tilde{\Delta}_1$ state possibly suitable for realizing a spin-dependent symmetry filter effect., Comment: 11 pages, 3 figures

One of the biggest challenges the current STT-RAM industry faces is maintaining a high thermal stability while trying to switch within a given voltage pulse and energy cost. In this paper, we present a physics based analytical model that uses a modified Simmons' tunneling expression to capture the spin dependent tunneling in a magnetic tunnel junction(MTJ). Coupled with an analytical derivation of the critical switching current based on the Landau-Lifshitz-Gilbert equation, and the write error rate derived from a solution to the Fokker-Planck equation, this model provides us a quick estimate of the energydelay- reliability tradeoffs in perpendicular STTRAMs due to thermal fluctuations. In other words, the model provides a simple way to calculate the energy consumed during a write operation that ensures a certain error rate and delay time, while being numerically far less intensive than a full-fledged stochastic calculation. We calculate the worst case energy consumption during anti-parallel (AP) to parallel (P) and P to AP switchings and quantify how increasing the anisotropy field HK and lowering the saturation magnetization MS, can significantly reduce the energy consumption. A case study on how manufacturing variations of the MTJ cell can affect the energy consumption and delay is also reported., Comment: 6 pages, 9 figures

We present a rational approach to the design of half-metallic heterostructures which allows the design of an infinite number of half-metallic heterostructures. The wide range of materials that can be made half-metallic using our approach makes it possible to engineer materials with tunable characteristic properties, for example low intrinsic magnetic damping, small magnetic moment or perpendicular anisotropy. We demonstrate the proposed design scheme for a series of transition metal heterostructures based on the B2 crystal structure.

We predict an anomalous bias dependence of the spin transfer torque parallel to interface, $T_{||}$, in magnetic tunnel junctions (MTJ), which can be selectively tuned by the exchange splitting. It may exhibit a sign reversal {\it without} a corresponding sign reversal of the bias or even a quadratic bias dependence. We demonstrate that the underlying mechanism is the interplay of spin currents for the ferromagnetic (antiferromagnetic) configurations, which vary linearly (quadratically) with bias, respectively, due to the symmetric (asymmetric) nature of the barrier. The spin transfer torque perpendicular to interface exhibits a quadratic bias dependence., Comment: 4 pages, 5 figures

Laser interferometer gravitational wave detectors can be operated at their free spectral range frequency. We show that in this case and when the interferometer is well understood one could detect a stochastic background using a single detector.