10 research outputs found
Magic angle effects of the one-dimensional axis conductivity in quasi-one dimensional conductors
In quasi-one-dimensional conductors, the conductivity in both one-dimensional
axis and interchain direction shows peaks when magnetic field is tilted at the
magic angles in the plane perpendicular to the conducting chain. Although there
are several theoretical studies to explain the magic angle effect, no
satisfactory explanation, especially for the one-dimensional conductivity, has
been obtained. We present a new theory of the magic angle effect in the
one-dimensional conductivity by taking account of the momentum-dependence of
the Fermi velocity, which should be large in the systems close to a spin
density wave instability. The magic angle effect is explained in the
semiclassical equations of motion, but neither the large corrugation of the
Fermi surface due to long-range hoppings nor hot spots, where the relaxation
time is small, on the Fermi surface are required.Comment: 4 pages, 3 figure
Comparison of coherent and weakly incoherent transport models for the interlayer magnetoresistance of layered Fermi liquids
The interlayer magnetoresistance of layered metals in a tilted magnetic field
is calculated for two distinct models for the interlayer transport. The first
model involves coherent interlayer transport and makes use of results of
semi-classical or Bloch-Boltzmann transport theory. The second model involves
weakly incoherent interlayer transport where the electron is scattered many
times within a layer before tunneling into the next layer. The results are
relevant to the interpretation of experiments on angular-dependent
magnetoresistance oscillations (AMRO) in quasi-one- and quasi-two-dimensional
metals. We find that the dependence of the magnetoresistance on the direction
of the magnetic field is identical for both models except when the field is
almost parallel to the layers. An important implication of this result is that
a three-dimensional Fermi surface is not necessary for the observation of the
Yamaji and Danner oscillations seen in quasi-two- and quasi-one-dimensional
metals, respectively. A universal expression is given for the dependence of the
resistance at AMRO maxima and minima on the magnetic field and scattering time
(and thus the temperature). We point out three distinctive features of coherent
interlayer transport: (i) a beat frequency in the magnetic oscillations of
quasi-two-dimensional systems, (ii) a peak in the angular-dependent
magnetoresistance when the field is sufficiently large and parallel to the
layers, and (iii) a crossover from a linear to a quadratic field dependence for
the magnetoresistance when the field is parallel to the layers. Properties (i)
and (ii) are compared with published experimental data for a range of
quasi-two-dimensional organic metals and for Sr2RuO4.Comment: 21 pages, RevTeX + epsf, 4 figures. Published version. Subsection
added. References update
Incoherent interlayer transport and angular-dependent magnetoresistance oscillations in layered metals
The effect of incoherent interlayer transport on the interlayer resistance of a layered metal is considered. We find that for both quasi-one-dimensional and quasi-two-dimensional Fermi liquids the angular dependence of the magnetoresistance is essentially the same for coherent and incoherent transport. Consequently, the existence of a three-dimensional Fermi surface is not necessary to explain the oscillations in the magnetoresistance that are seen in many organic conductors as the field direction is varied. [S0031-9007(98)07660-1]