Thermal switching of indirect interlayer exchange in magnetic multilayers

We propose a magnetic multilayer layout, in which the indirect exchange coupling (IEC also known as RKKY) can be switched on and off by a slight change in temperature. We demonstrate such on/off IEC switching in a Fe/Cr/FeCr-based system and obtain thermal switching widths as small as 10--20~K, essentially in any desired temperature range, including at or just above room temperature. These results add a new dimension of tunable thermal control to IEC in magnetic nanostructures, highly technological in terms of available materials and operating physical regimes.Comment: 3 figures, Supplementary Inf

Ferromagnetic resonance and interlayer exchange coupling in magnetic multilayers with compositional gradients

Ferromagnetic resonance (FMR) in magnetic multilayers of type F1/f/F2, where two strongly ferromagnetic layers F1 and F2 are separated by a weakly magnetic spacer f with a compositional gradient along its thickness, is investigated. The method allows to detect the weak signal from the spacer in additional to the more pronounced and readily measured signal from the outer strongly-magnetic layers, and thereby study the properties of the spacer as well as the interlayer exchange interaction it mediates. Variable temperature FMR measurements, especially near the relevant Curie points, reveal a rich set of properties of the exchange interactions in the system. The obtained results are useful for designing and optimizing nanostructures with thermally-controlled magnetic properties.Comment: 6 pages, 3 figure

Negative parity states of 11^{11}B and 11^{11}C and the similarity with $^{12}C

The negative parity states of $^{11}$B and $^{11}$C were studied based on the calculations of antisymmetrized molecular dynamics(AMD). The calculations well reproduced the experimental strengths of Gamov-Teller(GT), $M1$ and monopole transitions. We, especially, focused on the $3/2^-_3$ and $5/2^-_2$ states, for which GT transition strengths were recently measured. The weak $M1$ and GT transitions for the $3/2^-_3$ in $^{11}$B and $^{11}$C are described by a well-developed cluster structure of $2\alpha$+$t$ and $2\alpha$+$^3$He, respectively, while the strong transitions for the $5/2^-_2$ is characterized by an intrinsic spin excitation with no cluster structure. It was found that the $3/2^-_3$ state is a dilute cluster state, and its features are similar to those of the $^{12}$C$(0^+_2)$ which is considered to be a gas state of three $\alpha$ clusters.Comment: 10 pages, 4 figures, submitterd to Physical Review

Matrix Factorizations and Homological Mirror Symmetry on the Torus

We consider matrix factorizations and homological mirror symmetry on the torus T^2 using a Landau-Ginzburg description. We identify the basic matrix factorizations of the Landau-Ginzburg superpotential and compute the full spectrum, taking into account the explicit dependence on bulk and boundary moduli. We verify homological mirror symmetry by comparing three-point functions in the A-model and the B-model.Comment: 41 pages, 9 figures, v2: reference added, minor corrections and clarifications, version published in JHE

Cohomology Groups of Deformations of Line Bundles on Complex Tori

The cohomology groups of line bundles over complex tori (or abelian varieties) are classically studied invariants of these spaces. In this article, we compute the cohomology groups of line bundles over various holomorphic, non-commutative deformations of complex tori. Our analysis interpolates between two extreme cases. The first case is a calculation of the space of (cohomological) theta functions for line bundles over constant, commutative deformations. The second case is a calculation of the cohomologies of non-commutative deformations of degree-zero line bundles.Comment: 24 pages, exposition improved, typos fixe