arXiv subjects

Z. Fang

Publications and source records attributed to Z. Fang.

57 records · Page 4Linked to original sources

arXiv2001

Strong ferromangnetism and weak antiferroamgnetism in double perovskites: Sr$_2$Fe{/it M}O$_6$ ({/it M}=Mo, W and Re)

Double perovskites Sr$_2$FeMO$_6$ (M=Mo and Re) exhibit significant colossal magnetoresistance even at room temperature due to the high Curie Temperature (419K and 401K). However, such a high Curie Temperature is puzzling, given the large separation between magnetic elements (Fe). Moreover, with M=W, the electronic and magnetic properties suddenly change to insulating and antiferromagnetic with the N{é}el temperature of only 16$\sim$37 K. Based on detailed electronic structure calculations, a new mechanism is proposed which stabilizes the strong ferromagnetic state for M=Mo and Re and is passivated for M=W.

cond-mat.mtrl-sci↗

arXiv2000

Simulation of Returning Electrons from a Klystron Collector

Spurious oscillations in klystrons due to returning electrons from the collector into the drift tube were observed and studied at KEK. Simulations of returning electrons using EGS4 Monte Carlo method have been performed. And the oscillation conditions are described in this paper.

physics.acc-ph↗

arXiv1997

Inverse versus Normal NiAs Structure as High-Pressure Phase of FeO and MnO

The high-pressure phases of FeO and MnO were studied by the first principles calculations. The present theoretical study predicts that the high-pressure phase of MnO is a metallic normal B8 structure (nB8), while that of FeO should take the inverse B8 structure (iB8). The novel feature of the unique high-pressure phase of stoichiometric FeO is that the system should be a band insulator in the ordered antiferromagnetic (AF) state and that the existence of a band gap leads to special stability of the phase. The observed metallicity of the high-pressure and high-temperature phase of FeO may be caused by the loss of AF order and also by the itinerant carriers created by non-stoichiometry. Analysis of x-ray diffraction experiments provides a further support to the present theoretical prediction for both FeO and MnO. Strong stability of the high-pressure phase of FeO will imply possible important roles in Earth's core.

cond-mat.mtrl-sci↗