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Register a new userResistivity Calculations for Cuprate Superconductor Systems using an Electronic Phase Separation
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Added by
Evandro V. L. de Mello
Publication date
2011
fields
Physics
and research's language is
English
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The resistivity as function of temperature of high temperature superconductors is very unusual and despite its importance lacks an unified theoretical explanation. It is linear with the temperature for overdoped compounds but it falls more quickly as the doping level decreases, and for weakly doped samples it has a minimum, increases like an insulator before it drops to zero at low temperatures. We show that this overall behavior can be explained by calculations using an electronic phase segregation into two main component phases with low and high densities. The total resistivity is calculated by the various contributions through several random picking processes of the local resistivities and using the Random Resistor Network approach.
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We present a combined neutron diffraction (ND) and high-field muon spin rotation ($mu$SR) study of the magnetic and superconducting phases of the high-temperature superconductor La$_{1.94}$Sr$_{0.06}$CuO$_{4+y}$ ($T_{c} = 38$~K). We observe a linear dependence of the ND signal from the modulated antiferromagnetic order (m-AFM) on the applied field. The magnetic volume fraction measured with $mu$SR increases linearly from 0% to $sim$40% with applied magnetic field up to 8~T. This allows us to conclude, in contrast to earlier field-dependent neutron diffraction studies, that the long-range m-AFM regions are induced by an applied field, and that their ordered magnetic moment remains constant.
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