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Andrew Das Arulsamy

Publications and source records attributed to Andrew Das Arulsamy.

41 records · Page 3Linked to original sources
arXiv2004

Hall-Lorenz ratio of YBa2Cu3O7 using Ionization energy based Fermi-Dirac statistics and charge-spin separation

The temperature dependent properties of heat capacity, heat conductivity and Hall-Lorenz ratio have been solved numerically after taking the previously proposed ionization energy based Fermi-Dirac statistics and the coexistence of Fermi and charge-spin separated liquid into account. The thermo-magneto-electronic properties are entirely for spin and charge carriers, hence the phonon contribution has been neglected. A linear dependence between the Hall-Lorenz ratio and temperature ($T$) is also obtained in accordance with the experimental results for overdoped YBa$_2$Cu$_3$O$_{7-δ}$, if these conditions, $E_I$ $<$ $T_c$ with respect to resistivity and there are no spinon pairings ($T^*$ = 0) are satisfied. Heat conductivity based on both pure and electron-contaminated charge-spin separated liquid in $ab$-planes above $T_c$ are found to increase with decreasing $T$ as a consequence of inverse proportionality with $T$. The $T$-dependence of heat capacity are also highlighted, which qualitatively complies with the experimental findings.

cond-mat.supr-con↗
arXiv2004

Transport theory in the normal state of high-$T_c$ superconductors

Transport mechanism in the normal state of high-$T_c$ superconductors is described using the well known Fermi-Dirac statistics in which an additional restrictive constraint is introduced so as to capture the variation of resistivity with temperature and doping. The additional restrictive condition is the ionization energy that will eventually determine the properties of charge carriers' in the normal state of high-$T_c$ superconductors. The magnitude and the variation of charge carriers concentration and resistivities (polycrystalline, c-axis and $ab$-planes) with temperature and doping are very well described by the ionization energy based Fermi-Dirac statistics. However, these transport models are not appropriate for cuprates below the characteristics ($T^*$) and critical temperatures ($T_c$), metals with free electrons and strong electron-phonon scattering. Ionization energy is found to be an essential parameter to accurately predict variations of resistivity's magnitude with doping, charge carriers' concentrations, scattering rate constants as well as the effective mass. Apart from that, iFDS based resistivity models provide the comprehensive information on crossover-temperature (metallic $\to$ insulating transition temperature) in the normal state of high-$T_c$ superconductors.

cond-mat.stat-mech↗
arXiv2002

Pseudogap and Conduction Dimensionalities in High-T_c Superconductors

The nature of normal state charge-carriers' dynamics and the transition in conduction and gap dimensionalities between 2D and 3D for YBa_2 Cu_3 O_{7-delta} and Bi_2 Sr_2 Ca_{1-x} Y_x Cu_2 O_8 high-T_c superconductors were described by computing and fitting the resistivity curves, rho(T,delta,x). These were carried out by utilizing the 2D and 3D Fermi liquid (FL) and ionization energy (E_I) based resistivity models coupled with charge-spin (CS) separation based t-J model [Phys. Rev. B 64, 104516 (2001)]. rho(T,delta,x) curves of Y123 and Bi2212 samples indicate the beginning of the transition of conduction and gap from 2D to 3D with reduction in oxygen content (7-delta) and Ca^{2+} (1-x) as such, c-axis pseudogap could be a different phenomenon from superconductor and spin gaps. These models also indicate that the recent MgB_2 superconductor is at least not Y123 or Bi2212 type.

cond-mat.supr-con↗
arXiv2002

Concentration of Charge Carriers and Anomalous Gap Parameter in the Normal State of High-$T_c$ Superconductors

Fermi-Dirac statistics has been utilized by introducing the average ionization energy ($E_I$) as an additional anomalous energy gap in order to derive the two-dimensional concentration of charge carriers and the phenomenological resistivity model for the superconducting polycrystalline materials. The best fitted values of $E_I$ and the charge carriers' concentration ranges in the vicinity of 4 to 9 meV and 10$^{16}$ m$^{-2}$ respectively for the superconducting single crystal samples and polycrystalline compounds synthesized with various compositions via solid-state reactions. The phenomenological resistivity model is further redefined here based on the gapless nature of charge-carriers' dynamics within the Cu-O$_2$ planes that corresponds to anomalous Fermi liquid behavior, which is in accordance with the nested Fermi liquid theory.

cond-mat.supr-con↗