The metal-insulator transition （MIT） of VO2 （M） nanorods was studied. It was found that there were two MITs in the differential scanning calorimetry （DSC） curves of the VO2（M） nanorods, one situated at low tem...The metal-insulator transition （MIT） of VO2 （M） nanorods was studied. It was found that there were two MITs in the differential scanning calorimetry （DSC） curves of the VO2（M） nanorods, one situated at low temperature from -3 ℃ to 19 ℃ and the other was at high temperature of 65-74℃. The low temperature MIT was always accompanied with VO2（B） nanorods, and the high temperature MIT existed singly only in pure VO2（M） nanorods. The mechanisms of these two MITs were analyzed and discussed.展开更多
We report a density functional theory study of a phase transition of a VS2 monolayer that can be tuned by the in-plane biaxial strain. This results in both a metal-insulator transition and a low spin-high spin magneti...We report a density functional theory study of a phase transition of a VS2 monolayer that can be tuned by the in-plane biaxial strain. This results in both a metal-insulator transition and a low spin-high spin magnetic transition. At low temperature, the semiconducting H-phase is stable and large strain （〉3%） is required to provoke the transition. On the other hand, at room temperature （300 K）, only a small tensile strain of 2% is needed to induce the phase transition from the semiconducting H-phase to the metallic T-phase together with the magnetic transition from high spin to low spin. The phase diagram dependence on both strain and temperature is also discussed in order to provide a better understanding of the phase stability of VS2 monolayers.展开更多
After successfully growing single-crystal TaP, we measured its longitudinal resistivity （Pxx） and Hall resistivity （Pyx） at magnetic fields up to 9 T in the temperature range of 2-300 K. At 8 T, the magnetoresista...After successfully growing single-crystal TaP, we measured its longitudinal resistivity （Pxx） and Hall resistivity （Pyx） at magnetic fields up to 9 T in the temperature range of 2-300 K. At 8 T, the magnetoresistance （MR） reached 3.28 ×10^5% at 2 K, 176% at 300 K. Neither value appeared saturated. We confirmed that TaP is a hole-electron compensated semimetal with a low carrier concentration and high hole mobility ofμh=3.71 × 105 cm2/V s, and found that a magnetic-field-induced metal-insulator transition occurs at room temperature. Remarkably, because a magnetic field （H） was applied in parallel to the electric field （E）, a negative MR due to a chiral anomaly was observed and reached -3000% at 9 T without any sign of saturation, either, which is in contrast to other Weyl semimetals （WSMs）. The analysis of the Shubnikov-de Haas （SdH） oscillations superimposed on the MR revealed that a nontrivial Berry＇s phase with a strong offset of 0.3958, which is the characteristic feature of charge carriers enclosing a Weyl node. These results indicate that TaP is a promising candidate not only for revealing fundamental physics of the WSM state but also for some novel applications.展开更多
基金V. ACKNOWLEDGMENTS This work was financially Natural Science Foundation supported by the National of China （No.51372250）.
文摘The metal-insulator transition （MIT） of VO2 （M） nanorods was studied. It was found that there were two MITs in the differential scanning calorimetry （DSC） curves of the VO2（M） nanorods, one situated at low temperature from -3 ℃ to 19 ℃ and the other was at high temperature of 65-74℃. The low temperature MIT was always accompanied with VO2（B） nanorods, and the high temperature MIT existed singly only in pure VO2（M） nanorods. The mechanisms of these two MITs were analyzed and discussed.
文摘We report a density functional theory study of a phase transition of a VS2 monolayer that can be tuned by the in-plane biaxial strain. This results in both a metal-insulator transition and a low spin-high spin magnetic transition. At low temperature, the semiconducting H-phase is stable and large strain （〉3%） is required to provoke the transition. On the other hand, at room temperature （300 K）, only a small tensile strain of 2% is needed to induce the phase transition from the semiconducting H-phase to the metallic T-phase together with the magnetic transition from high spin to low spin. The phase diagram dependence on both strain and temperature is also discussed in order to provide a better understanding of the phase stability of VS2 monolayers.
基金supported by the National Basic Research Program of China(Grant Nos.2015CB9210042012CB821404 and 2011CBA00103)+2 种基金the National Natural Science Foundation of China(Grant Nos.11374261and 11204059)Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ12A04007)the Fundamental Research Funds for the Central Universities of China
文摘After successfully growing single-crystal TaP, we measured its longitudinal resistivity （Pxx） and Hall resistivity （Pyx） at magnetic fields up to 9 T in the temperature range of 2-300 K. At 8 T, the magnetoresistance （MR） reached 3.28 ×10^5% at 2 K, 176% at 300 K. Neither value appeared saturated. We confirmed that TaP is a hole-electron compensated semimetal with a low carrier concentration and high hole mobility ofμh=3.71 × 105 cm2/V s, and found that a magnetic-field-induced metal-insulator transition occurs at room temperature. Remarkably, because a magnetic field （H） was applied in parallel to the electric field （E）, a negative MR due to a chiral anomaly was observed and reached -3000% at 9 T without any sign of saturation, either, which is in contrast to other Weyl semimetals （WSMs）. The analysis of the Shubnikov-de Haas （SdH） oscillations superimposed on the MR revealed that a nontrivial Berry＇s phase with a strong offset of 0.3958, which is the characteristic feature of charge carriers enclosing a Weyl node. These results indicate that TaP is a promising candidate not only for revealing fundamental physics of the WSM state but also for some novel applications.
