arXiv subjects

I. E. Trofimov

Publications and source records attributed to I. E. Trofimov.

5 recordsLinked to original sources

arXiv1997

Normal-State Hall Effect and the Insulating Resistivity of High-T_c Cuprates at Low Temperatures

The normal-state Hall coefficient R_H and the in-plane resistivity ρ_{ab} are measured in La-doped Bi_{2}Sr_{2}CuO_{y} (T_c \simeq 13 K) single crystals and La_{2-x}Sr_{x}CuO_{4} thin films by suppressing superconductivity with 61-T pulsed magnetic fields. In contrast to data above T_c, the R_H below \sim 10 K shows little temperature dependence in all the samples measured, irrespective of whether ρ_{ab} exhibits insulating or metallic behavior. Thus, whatever physical mechanism gives rise to insulating behavior in the low-temperature normal state, it leaves the Hall conductivity relatively unchanged.

cond-mat.supr-con↗

arXiv1997

Orbital Magnetoresistance in the LaSrCuO System

Measurements of resistivity, Hall effect, and magnetoresistance have been made on seven c-axis oriented thin-film specimens of La(2-x)Sr(x)CuO(4) with values of x from 0.048 to 0.275, and one specimen that also contains Nd. The orbital magnetoresistance is found not to be proportional to the square of the tangent of the Hall angle except for values of x near 0.15 above about 80K. For smaller values of x the temperature dependence of the magnetoresistance is different, but quite similar in the various specimens, in spite of large differences in resistivity, Hall coefficient, and Hall angle.

cond-mat.supr-con↗

arXiv1994

Complex conductivity of $\rm Y_{1-x}Pr_xBa_2Cu_3O_7$ thin films measured by coherent terahertz spectroscopy

The complex transmission of Y_{1-x}Pr_xBa_2Cu_3O_7 single crystal thin films has been measured in the range 0.2-1.0 THz using time domain spectroscopy. The complex conductivity is calculated without using a Kramers-Kronig analysis. All of the superconducting samples show a peak in $σ_1(T)$ below $T_c$. The underdoped samples show a deviation from $1/(α+βT)$ behavior above $T_c$ that may be linked with the onset of a spin gap.

cond-mat↗

arXiv1994

Anomalous Behavior Of The Complex Conductivity Of Y_{1-x}Pr_xBa_2Cu_3O_7 Observed With THz Spectroscopy

We have measured the electrodynamic properties of Y_{1-x}Pr_xBa_2Cu_3O_7 single crystal thin films as a function of temperature using coherent THz-time-domain spectroscopy. We obtain directly the complex conductivity $σ=σ_1+iσ_2$, the London penetration depth $λ_L$, the plasma frequency $ω_p$, and the quasiparticle scattering rate $1/τ$. We find that $1/τ$ drops exponentially rapidly with $T$ below the critical temperature in {\em all} the superconducting samples, implying that this behavior is a {\em signature} of high-$T_c$ superconductivity. The plasma frequency decreases with increasing Pr content, providing evidence that Pr depletes carriers, leaving the CuO planes {\em underdoped}. Both the conductivity in the THz region and the dc resistivity yield evidence for the opening of a spin gap {\em above} $T_c$.

cond-mat↗

arXiv1993

Kinetic Inductance and Penetration Depth of Thin Superconducting Films Measured by THz Pulse Spectroscopy

We measure the transmission of THz pulses through thin films of YBCO at temperatures between 10K and 300K. The pulses possess a useable bandwidth extending from 0.1 -- 1.5 THz (3.3 cm^-1 -- 50 cm^-1). Below T_c we observe pulse reshaping caused by the kinetic inductance of the superconducting charge carriers. From transmission data, we extract values of the London penetration depth as a function of temperature, and find that it agrees well with a functional form (λ(0)/λ(T))^2 = 1 - (T/T_c)^α, where λ(0) = 148 nm, and α= 2. *****Figures available upon request*****

cond-mat↗