Magnetic-field influence on the collective properties of charge- and spin-density waves

The influence of an external magnetic field on a quasi one-dimensional system with a charge density wave (CDW) instability is treated within the random phase approximation (RPA) which includes both CDW and spin density wave (SDW) correlations. We show that the CDW is sensitive to both orbital and Pauli effects of the field. In the case of perfect nesting, the critical temperature decreases monotonously with the field, and the wave vector of the instability starts to shift above some critical value of magnetic field. Depending on the ratio between the spin and charge coupling constants and on the direction of the applied magnetic field, the wave vector shift is either parallel (CDW x order) or perpendicular (CDW y order) to the most conducting direction. The CDW x order is a field dependent linear combination of the charge and spin density waves and is sensible only to the Pauli effect. The wave vector shift in CDW y depends on the interchain coupling, but the critical temperature does not. This order is affected by the confinement of the electronic orbits. By increasing the relative strength of the orbital effect with respect to the Pauli effect, one can destroy the CDW y , establishing either a CDW x , or a CDW 0 (corresponding to perfect nesting wave vector). We also show that by increasing the imperfect nesting parameter, one passes from the regime where the critical temperature decreases with the field to the regime where it is initially enhanced by the orbital effect and eventually suppressed by the Pauli effect. For a bad nesting, the quantized phases of the field-induced CDW appear.

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“…For T = T c (H) it suffices to expand the [..] bracket in eq. (13). Noting that there is no bilinearly mixed term (q x q y ), one gets…”

Section: Discussionmentioning

confidence: 99%

“…On the other side, the orbital coupling alone leads to an increase of the critical temperature for CDW s [11,12,13]. Such an increase was observed in e. g. NbSe 3 [14].…”

Section: Introductionmentioning

confidence: 98%

Phase diagram for charge-density waves in a magnetic field

1996

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“…Nevertheless, it always manifests itself in CDW metals or insulators and can even modify the very CDW wave vector [21][22][23][24][25]. Therefore, in calculating the total response both the paramagnetic (spin) and diamagnetic contributions should be taken into account [18,[26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Paramagnetic effect of magnetic field on superconductors with charge-density waves

Ekino

Gabovich

Войтенко

2005

Low Temperature Physics

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The limiting field H p for spin-singlet superconductors with charge-density waves (CDWs), which paramagnetically destroys the ordered phase, possessing coexisting superconducting and CDW order parameters, is calculated self-consistently. It is shown that H p always exceeds the Pauli limits both for pure superconducting and pure CDW phases. Relevant experimental data for inorganic and organic superconductors with high upper critical magnetic fields are analyzed and are shown to be in qualitative agreement with the proposed theory.

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“…The external magnetic field H influences the spin density wave (SDW) order through the orbital and Pauli coupling. The orbital coupling may lead to the field induced stabilization of SDW [l -31, or to the increase of critical temperature in systems with SDW already existing at H = 0 [4]. Furthermore, this mechanism also causes the decrease of the transverse correlation lengths (even if the nesting is perfect) [5] and the angular resonances of Lebed's [6] type whenever the magnetic lengths in the two transverse directions are commensurate [7,8].…”

Section: Introductionmentioning

confidence: 99%

Effects of Zeeman splitting on spin density waves

Bjelic

Zanchi

1993

J. Phys. IV France

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Starting from the Hubbard model with the repulsive Coulomb interaction and imperfectly nested Fermi surfaces we calculate the total, i.e. spin and charge density wave, 2kF-susceptibility above the critical temperature, taking into account both, orbital and spin coupling of electrons to the external magnetic field H. The influence of the magnetic field on the collective modes, and in particular the emerging splitting of degeneracies present in the isotropic case (H = 0), are also discussed

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Magnetic-field influence on the collective properties of charge- and spin-density waves

Cited by 16 publications

References 13 publications

Phase diagram for charge-density waves in a magnetic field

Phase diagram for charge-density waves in a magnetic field

Paramagnetic effect of magnetic field on superconductors with charge-density waves

Effects of Zeeman splitting on spin density waves

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