arXiv subjects

Xiaoshan Xu

Publications and source records attributed to Xiaoshan Xu.

57 records · Page 4Linked to original sources

arXiv2012

Growth diagram and magnetic properties of hexagonal LuFe$_2$O$_4$ thin films

A growth diagram of Lu-Fe-O compounds on MgO (111) substrates using pulsed laser deposition is constructed based on extensive growth experiments. The LuFe$_2$O$_4$ phase can only be grown in a small range of temperature and O$_2$ pressure conditions. An understanding of the growth mechanism of Lu-Fe-O compound films is offered in terms of the thermochemistry at the surface. Superparamagnetism is observed in LuFe$_2$O$_4$ film and is explained in terms of the effect of the impurity h-LuFeO$_3$ phase and structural defects .

cond-mat.mtrl-sci↗

arXiv2010

Bistability of Free Cobalt and Iron Clusters

The cobalt and iron clusters CoN, FeN (20 < N < 150) measured in a cryogenic molecular beam are found to be bistable with magnetic moments per atom both μN/N 2μB in the ground states and μN */N μB in the metastable excited states (for iron clusters, μN ~3NμB and μN* NμB). This energy gap between the two states vanish for large clusters, which explains the rapid convergence of the magnetic moments to the bulk value and suggests that ground state for the bulk involves a superposition of the two, in line with the fluctuating local orders in the bulk itinerant ferromagnetism.

cond-mat.str-el↗

arXiv2006

Non-classical dipoles in cold niobium clusters

Electric deflections of niobium clusters in molecular beams show that they have permanent electric dipole moments at cryogenic temperatures but not higher temperatures, indicating that they are ferroelectric. Detailed analysis shows that the deflections cannot be explained in terms of a rotating classical dipole, as claimed by Anderson et al. The shapes of the deflected beam profiles and their field and temperature dependences indicates that the clusters can exist in two states, one with a dipole and the other without. Cluster with dipoles occupy lower energy states. Excitations from the lower states to the higher states can be induced by low fluence laser excitation. This causes the dipole to vanish.

cond-mat.str-el↗