Magnetic field effects in electron systems with imperfect nesting

“…(12) and (14), the two sectors σ are decoupled within the mean-field approach. Then, applying a well-known procedure 23,24,31 , one can calculate the order parameters ∆ σ and the chemical potential µ as functions of x σ . This gives the following expression…”

Section: A Sdw Instability and Spin-valley Half-metalmentioning

confidence: 99%

Spin-valley half-metal in systems with Fermi surface nesting

et al. 2018

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Half-metals have fully spin polarized charge carriers at the Fermi surface. Such polarization usually occurs due to strong electron-electron correlations. Recently [Phys. Rev. Lett. 119, 107601 (2017)], we have demonstrated theoretically that adding (or removing) electrons to systems with Fermi surface nesting also stabilizes the half-metallic states even in the weak-coupling regime. In the absence of doping, the ground state of the system is a spin or charge density wave, formed by four nested bands. Each of these bands is characterized by charge (electron/hole) and spin (up/down) labels. Only two of these bands accumulate charge carriers introduced by doping, forming a halfmetallic two-valley Fermi surface. Analysis demonstrates that two types of such half-metallicity can be stabilized. The first type corresponds to the full spin polarization of the electrons and holes at the Fermi surface. The second type, with antiparallel spins in electron-like and hole-like valleys, is referred to as a "spin-valley half-metal" and corresponds to the complete polarization with respect to the spin-valley operator. We analyze spin and spin-valley currents and possible superconductivity in these systems. We show that spin or spin-valley currents can flow in both half-metallic phases.

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“…While the single-layer graphene physics cannot generate the ordering transition for U < U c , it affects the magnitude of ∆ significantly: large factor exp(1/(ρ 0 U c )) in Eq. (42) introduces strong renormalization of pre-exponential energy scale t 0 .…”

Section: A Single-layer Graphene Physics In Sdw Transitionmentioning

confidence: 99%

“…Red solid curve is found numerically by solving Eq. (34), while dashed blue curve corresponds to approximate formula(42). Inset shows the dependence of ∆ on t0 calculated by solving Eq.…”

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confidence: 99%

Spin-density wave state in simple hexagonal graphite

et al. 2018

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Simple hexagonal graphite, also known as AA graphite, is a metastable configuration of graphite. Using tight-binding approximation it is easy to show that AA graphite is a metal with well-defined Fermi surface. The Fermi surface consists of two sheets, each shaped like a rugby ball. One sheet corresponds to electron states, another corresponds to hole states. The Fermi surface demonstrates good nesting: a suitable translation in the reciprocal space superposes one sheet onto another. In the presence of the electron-electron repulsion a nested Fermi surface is unstable with respect to spindensity wave ordering. This instability is studied using the mean-field theory at zero temperature, and the spin-density wave order parameter is evaluated.PACS numbers:

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Magnetic field effects in electron systems with imperfect nesting

Cited by 12 publications

References 62 publications

Electronic phase separation: Recent progress in the old problem

Electronic phase separation: Recent progress in the old problem

Spin-valley half-metal in systems with Fermi surface nesting

Spin-density wave state in simple hexagonal graphite

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