arXiv subjects

Mun-Seog Kim

Publications and source records attributed to Mun-Seog Kim.

22 records · Page 2Linked to original sources

arXiv2001

Hole carrier in MgB_{2} characterized by Hall Measurements

The longitudinal resistivity rho_{xx} and Hall coefficient R_H were measured for MgB2 sintered under high pressure. We found that R_H is positive like cuprate high-Tc superconductors, and decreases as the temperature increases for 40 K < T < 300 K. The cotangent of the Hall angle was found to follow a+bT^2 behavior from Tc to 300 K. At T = 100 K, R_H = 4.1 x 10^{-11} m^3/C from which hole carrier density was determined to be 1.5 x 10^{23}/cm^3. This carrier density is 2 - 3 orders of magnitude larger than that of Nb3Sn superconductor and that of optimally doped YBa_2Cu_3O_y.

cond-mat.supr-con↗

arXiv2000

Synthesis and characterization of the infinite-layer superconductor Sr_{0.9}La_{0.1}CuO_{2}

We report the high-pressure synthesis of the electron-doped infinite-layer superconductor Sr_{0.9}La_{0.1}CuO_{2}. A Rietveld analysis using X-ray powder diffraction data showed that, within the resolution of the measurement, the sample was purely an infinite-layer structure without any discernible impurities. The superconducting volume fraction and the transition width were greatly improved compared to those in the previous reports. Also the irreversibility field line was much higher than that of (La,Sr)_{2}CuO_{4}. The higher value seems to originate from the strong interlayer coupling due to the reduced average distance between the CuO_{2} planes.

cond-mat.supr-con↗

arXiv2000

Two-Dimensional Nature of Four-Layer Superconductors by Inequivalent Hole Distribution

The magnetization of the four-layer superconductor CuBa_{2}Ca_{3}Cu_4O_{12-δ} with T_c\simeq117 K is presented. The high-field magnetization around T_c(H) follows the exact two-dimensional scaling function given by Tešanović and Andreev. This feature is contrary to the inference that the interlayer coupling becomes strong if the number of CuO_2 planes in a unit cell increases. Also, the fluctuation-induced susceptibility in the low-field region was analyzed by using the modified Lawrence-Doniach model. The effective number of independently fluctuating CuO_2 layers per unit cell, g_{\rm eff}, turned out to be \simeq 2 rather than 4, which indicated that two among the four CuO_2 layers were in states far from their optimal doping levels. This result could explain why CuBa_{2}Ca_{3}Cu_4O_{12-δ} shows two-dimensional behavior.

cond-mat.supr-con↗

arXiv1999

Temperature-scaling behavior of the Hall conductivity for Hg-based superconducting thin films

The Hall conductivities of HgBa_{2}CaCu_{2}O_{6+δ}and HgBa_{2}Ca_{2}Cu_{3}O_{8+δ} thin films are investigated for a magnetic field parallel to the c axis. The mixed-state Hall conductivity for these compounds is well described by σ_{xy}=C_{1}/H+C_{2}+C_{3}H. The prefactor C_1 shows a temperature dependence of the form C_1 = A(1-t)^n near T_c, where t=T/T_c is the reduced temperature. Contrary to the previous results, C_2 also follows a temperature-scaling behavior similar to that of the coefficient C_1. The observed value of n = 1.8 - 2.3 is comparable to the previously observed values for YBa_{2}Cu_{3}O_{7-δ} and La_{2-x}Sr_{x}CuO_{4}.

cond-mat.supr-con↗