The variations of pauli spin paramagnetic susceptibility and the electronic specific heat of solids, are caiculated as functions of temperature following the free electron approximation, in generalised d-dimensions. T...The variations of pauli spin paramagnetic susceptibility and the electronic specific heat of solids, are caiculated as functions of temperature following the free electron approximation, in generalised d-dimensions. The results are compared and become consistent with that obtained in susceptibility becomes independent of temperature only in three dimensions. Interestingly, the Pauli spin paramagnetic two dimensions.展开更多
A repulsive vortex\|vortex interaction model was used to numerically study the melting transition of the two\|dimensional vortex system with Monte Carlo method. Then a δ\|function\|like peak in the specific heat was ...A repulsive vortex\|vortex interaction model was used to numerically study the melting transition of the two\|dimensional vortex system with Monte Carlo method. Then a δ\|function\|like peak in the specific heat was observed and the internal energy showed a sharp drop at the melting temperature, which indicated that there exists a first\|order melting transition at finite temperatures. The Lindemann criterion was also investigated and valid, but different from previous simulation results.展开更多
In the present paper, we study effect of the long-range Coulomb interaction on the thermodynamic propertiesof graphene by renormalization group methods.Our calculations show that both the specific heat and the magneti...In the present paper, we study effect of the long-range Coulomb interaction on the thermodynamic propertiesof graphene by renormalization group methods.Our calculations show that both the specific heat and the magneticsusceptibility of the material behave differently from the Landau Fermi liquid.More precisely, we find that thesequantities are logarithmically suppressed with respect to its noninteracting counterpart when temperature is low.展开更多
在一些磁性材料内,磁性离子间交换作用和磁性离子的自旋涨落对材料磁性有影响.本文根据磁比热实验值确定了晶场参数后,利用包含自旋涨落的交换作用有效场Hm=n0(1+γT+βeωT)M,计算了Pr Ni2晶体晶场能级的Zeeman劈裂.在温度为3.8 K T 3...在一些磁性材料内,磁性离子间交换作用和磁性离子的自旋涨落对材料磁性有影响.本文根据磁比热实验值确定了晶场参数后,利用包含自旋涨落的交换作用有效场Hm=n0(1+γT+βeωT)M,计算了Pr Ni2晶体晶场能级的Zeeman劈裂.在温度为3.8 K T 30 K范围内,计算了该晶体多晶磁矩随外磁场的变化,以及外磁场H=5000 Oe时磁化率倒数随温度的变化,计算结果和实验值符合较好.当外磁场在0—50000 Oe时,计算的该晶体的磁熵变与已有文献的理论结果相似.计算结果说明,提出的包含自旋涨落的交换作用有效场不仅适合亚铁磁性晶体,而且也适合顺磁性晶体.展开更多
CoPt-TiO2 nanocomposite films were synthesized by rapid thermal annealing of CoPt/TiO2 multilayers.The effects of TiO2 volume fraction on the microstructure and magnetic properties of the nanocomposite films were stud...CoPt-TiO2 nanocomposite films were synthesized by rapid thermal annealing of CoPt/TiO2 multilayers.The effects of TiO2 volume fraction on the microstructure and magnetic properties of the nanocomposite films were studied.Results showed that the ordering and texture of the L10-CoPt particles did not change with TiO2 content up to 76 vol.% of TiO2.However,the volume of the L10-CoPt particles in the film decreased with an increase in TiO2 content.Increasing TiO2 content effectively reduced the coalescence of magnetic grains when TiO2 content was larger than 56 vol.%.Both the out-of-plane coercivity and remanence ratio of the film decreased slightly with TiO2 content,but the in-plane coercivity and remanence ratio of the film decreased firstly and then increased after TiO2 content was larger than 56 vol.%.The reduction in the coercivity of the film should be due to the reduction in the size of the L10-CoPt particles.The reduction in remanence ratio might be due to the weakening of the exchange coupling strength between the magnetic grains when TiO2 content was increased,as indicated by the MFM images.展开更多
文摘The variations of pauli spin paramagnetic susceptibility and the electronic specific heat of solids, are caiculated as functions of temperature following the free electron approximation, in generalised d-dimensions. The results are compared and become consistent with that obtained in susceptibility becomes independent of temperature only in three dimensions. Interestingly, the Pauli spin paramagnetic two dimensions.
文摘A repulsive vortex\|vortex interaction model was used to numerically study the melting transition of the two\|dimensional vortex system with Monte Carlo method. Then a δ\|function\|like peak in the specific heat was observed and the internal energy showed a sharp drop at the melting temperature, which indicated that there exists a first\|order melting transition at finite temperatures. The Lindemann criterion was also investigated and valid, but different from previous simulation results.
基金Supported by the Chinese National Science Foundation under Grant No.10874003 by Ministry of Science and Technology of China under Grant No.2006CB921300
文摘In the present paper, we study effect of the long-range Coulomb interaction on the thermodynamic propertiesof graphene by renormalization group methods.Our calculations show that both the specific heat and the magneticsusceptibility of the material behave differently from the Landau Fermi liquid.More precisely, we find that thesequantities are logarithmically suppressed with respect to its noninteracting counterpart when temperature is low.
文摘在一些磁性材料内,磁性离子间交换作用和磁性离子的自旋涨落对材料磁性有影响.本文根据磁比热实验值确定了晶场参数后,利用包含自旋涨落的交换作用有效场Hm=n0(1+γT+βeωT)M,计算了Pr Ni2晶体晶场能级的Zeeman劈裂.在温度为3.8 K T 30 K范围内,计算了该晶体多晶磁矩随外磁场的变化,以及外磁场H=5000 Oe时磁化率倒数随温度的变化,计算结果和实验值符合较好.当外磁场在0—50000 Oe时,计算的该晶体的磁熵变与已有文献的理论结果相似.计算结果说明,提出的包含自旋涨落的交换作用有效场不仅适合亚铁磁性晶体,而且也适合顺磁性晶体.
基金supported by the Agency for Science, Technology and Research (ASTAR) Singapore (Grant No. 062-101-0021)FRC of NUS (Grant No. R-284-000-053-112)
文摘CoPt-TiO2 nanocomposite films were synthesized by rapid thermal annealing of CoPt/TiO2 multilayers.The effects of TiO2 volume fraction on the microstructure and magnetic properties of the nanocomposite films were studied.Results showed that the ordering and texture of the L10-CoPt particles did not change with TiO2 content up to 76 vol.% of TiO2.However,the volume of the L10-CoPt particles in the film decreased with an increase in TiO2 content.Increasing TiO2 content effectively reduced the coalescence of magnetic grains when TiO2 content was larger than 56 vol.%.Both the out-of-plane coercivity and remanence ratio of the film decreased slightly with TiO2 content,but the in-plane coercivity and remanence ratio of the film decreased firstly and then increased after TiO2 content was larger than 56 vol.%.The reduction in the coercivity of the film should be due to the reduction in the size of the L10-CoPt particles.The reduction in remanence ratio might be due to the weakening of the exchange coupling strength between the magnetic grains when TiO2 content was increased,as indicated by the MFM images.
