Peierls-type structural phase transition in a crystal induced by magnetic breakdown

We predict a new type of phase transition in a quasi-two dimensional system of electrons at high magnetic fields, namely the stabilization of a density wave which transforms a two dimensional open Fermi surface into a periodic chain of large pockets with small distances between them. The quantum tunneling of electrons between the neighboring closed orbits enveloping these pockets transforms the electron spectrum into a set of extremely narrow energy bands and gaps which decreases the total electron energy, thus leading to a magnetic breakdown induced density wave (MBIDW) ground state. We show that this DW instability has some qualitatively different properties in comparison to analogous DW instabilities of Peierls type. E. g. the critical temperature of the MBIDW phase transition arises and disappears in a peculiar way with a change of the inverse magnetic field

Competing SDW Phases and Quantum Oscillations in (TMTSF)2ClO4 in Magnetic Field

We propose a new approach for studying spin density waves (SDW) in the Bechgaard salt (TMTSF)2ClO4 where lattice is dimerized in transverse direction due to anion ordering. The SDW response is calculated in the matrix formulation that rigorously treats the hybridization of inter-band and intra-band SDW correlations. Since the dimerization gap is large, of the order of transverse bandwidth, we also develop an exact treatment of magnetic breakdown in the external magnetic field. The obtained results agree with the experimental data on the fast magneto-resistance oscillations. Experimentally found 260T rapid oscillations and the characteristic Tc dependance on magnetic field of relaxed material are fitted with our results for anion potential of the order of interchain hopping

Self-excited Oscillations of Charge-Spin Accumulation Due to Single-electron Tunneling

We theoretically study electronic transport through a layer of quantum dots connecting two metallic leads. By the inclusion of an inductor in series with the junction, we show that steady electronic transport in such a system may be unstable with respect to temporal oscillations caused by an interplay between the Coulomb blockade of tunneling and spin accumulation in the dots. When this instability occurs, a new stable regime is reached, where the average spin and charge in the dots oscillate periodically in time. The frequency of these oscillations is typically of the order of 1GHz for realistic values of the junction parameters

Coulomb-promoted spintromechanics in magnetic shuttle devices

Exchange forces on the movable dot ("shuttle") in a magnetic shuttle device depend on the parity of the number of shuttling electrons. The performance of such a device can therefore be tuned by changing the strength $U$ of Coulomb correlations to block or unblock parity fluctuations. We show that by increasing $U$ the spintro-mechanics of the device crosses over, at $U=U_c(T)$, from a mechanically stable regime to a regime of spin-induced shuttle instabilities. This is due to enhanced spin-dependent mechanical forces as parity fluctuations are reduced by a Coulomb blockade of tunneling and demonstrates that single-electron manipulation of single-spin controlled nano-mechanics is possible.Comment: 5 pages, 2 figures and a supplementary information fil

Spin-Polaronic Effects in Electric Shuttling in a Single Molecule Transistor with Magnetic Leads

Current-voltage characteristics of a spintromechanical device, in which spin-polarized electrons tunnel between magnetic leads with anti-parallel magnetization through a single level movable quantum dot, are calculated. New exchange- and electromechanical coupling-induced (spin-polaronic) effects that determine strongly nonlinear current-voltage characteristics were found. In the low-voltage regime of electron transport the voltage-dependent and exchange field-induced displacement of quantum dot towards the source electrode leads to nonmonotonic behavior of differential conductance that demonstrates the lifting of spin-polaronic effects by electric field. At high voltages the onset of electron shuttling results in the drop of current and negative differential conductance, caused by mechanically-induced increase of tunnel resistivities and exchange field-induced suppression of spin-flips in magnetic field. The dependence of these predicted spin effects on the oscillations frequency of the dot and the strength of electron-electron correlations is discussed.Comment: 8 pages, 4 figure