arXiv subjects

L. Zhao

Publications and source records attributed to L. Zhao.

98 records · Page 6Linked to original sources

arXiv2006

Intrinsic electron-doping in nominal "non-doped" superconducting (La,Y)$_2$CuO$_4$ thin films grown by dc magnetron sputtering

The superconducting nominal "non-doped" $La_{1.85}Y_{0.15}CuO_4$ (LYCO) thin films are successfully prepared by dc magnetron-sputtering and in situ post-annealing in vacuum. The best $T_{C0}$ more than 13K is achieved in the optimal LYCO films with highly pure c-axis oriented T'-type structure. In the normal state, the quasi-quadratic temperature dependence of resistivity, the negative Hall coefficient and effect of oxygen content in the films are quite similar to the typical Ce-doped T'-214 cuprates, suggesting that T'-LYCO shows the electron-doping nature like known n-type cuprates, and is not a band superconductor as proposed previously. The charge carriers are considered to be induced by oxygen deficiency.

cond-mat.supr-con↗

arXiv2006

Coexistence of Superconductivity and Ferromagnetism in Dilute Co-doped $La_{1.89} Ce_{0.11} Cu O_{4\pm\d}$ System

Thin films of the optimally electron-doped $T'$-phase superconductor La$_{1.89}$Ce$_{0.11}$CuO$_{4\pm \d}$ are investigated by dilute Co doping, formed as La$_{1.89}$Ce$_{0.11}$(Cu$_{1-x}$Co$_{x}$)O$_{4\pm\d}$ (LCCCO) with $x$ = 0.01 -- 0.05. The following results are obtained for the first time: for the whole dilute Co doping range, LCCCO thin films show long-range ferromagnetic ordering at the temperature range from 5 K to 300 K, which is likely due to the RKKY interaction; in the very dilute Co doping, $x$ = 0.01 and 0.02, the superconductivity is maitained, the system shows the coexistence of superconductivity and ferromagnetism in the CuO$_{2}$ plane. This may be based on the nature of the charge carriers in electron-doped high-$T_{c}$ cuprate superconductors.

cond-mat.supr-con↗

arXiv2004

Quantum-magneto oscillations in a supramolecular Mn(II)-[3 x 3] grid

The magnetic grid molecule Mn(II)-[3 x 3] has been studied by high-field torque magnetometry at 3He temperatures. At fields above 5 T, the torque vs. field curves exhibit an unprecedented oscillatory behavior. A model is proposed which describes these magneto oscillations well.

cond-mat↗

arXiv2002

Field dependent anisotropy change in a supramolecular Mn(II)-[3x3] grid

The magnetic anisotropy of a novel Mn(II)-[3x3] grid complex was investigated by means of high-field torque magnetometry. Torque vs. field curves at low temperatures demonstrate a ground state with S > 0 and exhibit a torque step due to a field induced level-crossing at B* \approx 7.5 T, accompanied by an abrupt change of magnetic anisotropy from easy-axis to hard-axis type. These observations are discussed in terms of a spin Hamiltonian formalism.

cond-mat↗

arXiv2001

Ambiguities of the Seiberg-Witten map in the presence of matter field

The ambiguities of the Seiberg-Witten map for gauge field coupled with fermionic matter are discussed. We find that only part of the ambiguities can be absorbed by gauge transformation and/or field redefinition and thus are negligible. The existence of matter field makes some other part of the ambiguities difficult to be absorbed by gauge transformation or field redefinition.

hep-th↗

arXiv1997

Boundary Exchange Algebras and Scattering on the Half Line

Some algebraic aspects of field quantization in space-time with boundaries are discussed. We introduce an associative algebra, whose exchange properties are inferred from the scattering processes in integrable models with reflecting boundary conditions on the half line. The basic properties of this algebra are established and the Fock representations associated with certain involutions are derived. We apply these results for the construction of quantum fields and for the study of scattering on the half line.

hep-th↗

arXiv1997

Free Boson Representation of $DY_{\hbar}(sl_2)_k$ and the Deformation of the Feigin-Fuchs

A realization of the Yangian double with center $DY_\hbar(sl_2)_k$ of level $k(\not=0,-2)$ in terms of free boson fields is constructed. The screening currents are also presented, which commute with $DY_\hbar(sl_2)$ modulo total difference. In the $\hbar\to 0$ limit, the currents of Yangian double $DY_\hbar(sl_2)_k$ becomes the Feigin-Fuchs realization of affine Lie $sl(2)_k$, while the screening currents of Yangian double $DY_\hbar(sl_2)_k$ becomes the screening currents of the affine Lie algebra $sl(2)_k$.

hep-th↗

arXiv1997

Free boson representation of DY_{\hbar}(gl_N)_k

We construct a realization of the Yangian double DY_\hbar(gl_N) and DY_\hbar(sl_N) of an arbitrary level k in terms of free boson fields with a continuous parameter. In the \hbar \to 0 limit this realization becomes the Wakimoto realization of kac-Moody algebra gl_N and sl_N, respectively. The vertex operators and the screening currents are also constructed with the same spirits; the screening currents commute with DY_\hbar(sl_N) modulo total difference.

hep-th↗