Theories and experiments on dirty superconductors are complex but important in terms of both theoretical fundamentals and practical applications.These activities are even more challenging when magnetic fields are pres...Theories and experiments on dirty superconductors are complex but important in terms of both theoretical fundamentals and practical applications.These activities are even more challenging when magnetic fields are present because the field distribution,electron density of states,and superconducting pairing potentials become nonuniform.Here,we present tunneling microspectroscopic experiments on NbC single crystals and demonstrate that NbC is a homogeneous dirty superconductor.When applying magnetic fields to the samples,we found that the zero-energy local density of states and the pairing energy gap followed the explicit scaling relation proposed by de Gennes for homogeneous dirty superconductors in high magnetic fields.More significantly,our experimental findings indicate that the validity of the scaling relation extends to magnetic field strengths far below the upper critical field,calling for a new nonperturbative understanding of this fundamental property in dirty superconductors.On the practical side,we used the observed scaling relation to derive a simple and straightforward experimental scheme for estimating the superconducting coherence length of a dirty superconductor in magnetic fields.展开更多
The effect of Pr,Nd addition on the magnetic properties and magnetic exchange interaction of gadolinium alloys was systematically studied.Curie temperature TC and magnetic moment of Gd（1–x）REx（RE=Pr,Nd）systems wi...The effect of Pr,Nd addition on the magnetic properties and magnetic exchange interaction of gadolinium alloys was systematically studied.Curie temperature TC and magnetic moment of Gd（1–x）REx（RE=Pr,Nd）systems with x〈0.05 were investigated.When x〈0.05,Pr and Nd formed respectively with Gd continuous solid solution which has the crystalline structure HCP.Study on the magnetic behavior indicated that at near room temperature,the simple ferromagnetism prevailed in these two systems of alloy.The Curie temperature and magnetic moment of Gd（1–x）REx alloy decreased with RE（RE= Pr,Nd）content x increasing.The de Gennes factor of Gd（1–x）REx alloy which was associated with the exchange interaction between magnetic spin components also decreased with RE content increasing.The above results showed that the magnetic exchange interaction between magnetic atoms in gadolinium could be effectively changed by the Pr,Nd addition.展开更多
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology of China(Grant Nos.2017YFA0302903,2016YFA0300602,2016YFA0300604,and 2016YFJC010282)the National Natural Science Foundation of China(Grant Nos.11227903,12004416,and U2032204)+3 种基金the Beijing Municipal Science and Technology Commission,China(Grant Nos.Z181100004218007 and Z191100007219011)the National Basic Research Program of China(Grant No.2015CB921304)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB07000000,XDB28000000 and XDB33000000)supported by the US Department of Energy(Basic Energy Sciences Grant No.DE-FG02-99ER45747).
文摘Theories and experiments on dirty superconductors are complex but important in terms of both theoretical fundamentals and practical applications.These activities are even more challenging when magnetic fields are present because the field distribution,electron density of states,and superconducting pairing potentials become nonuniform.Here,we present tunneling microspectroscopic experiments on NbC single crystals and demonstrate that NbC is a homogeneous dirty superconductor.When applying magnetic fields to the samples,we found that the zero-energy local density of states and the pairing energy gap followed the explicit scaling relation proposed by de Gennes for homogeneous dirty superconductors in high magnetic fields.More significantly,our experimental findings indicate that the validity of the scaling relation extends to magnetic field strengths far below the upper critical field,calling for a new nonperturbative understanding of this fundamental property in dirty superconductors.On the practical side,we used the observed scaling relation to derive a simple and straightforward experimental scheme for estimating the superconducting coherence length of a dirty superconductor in magnetic fields.
基金Project supported by the Key Project of National Natural Science Foundation of China(51176050)
文摘The effect of Pr,Nd addition on the magnetic properties and magnetic exchange interaction of gadolinium alloys was systematically studied.Curie temperature TC and magnetic moment of Gd（1–x）REx（RE=Pr,Nd）systems with x〈0.05 were investigated.When x〈0.05,Pr and Nd formed respectively with Gd continuous solid solution which has the crystalline structure HCP.Study on the magnetic behavior indicated that at near room temperature,the simple ferromagnetism prevailed in these two systems of alloy.The Curie temperature and magnetic moment of Gd（1–x）REx alloy decreased with RE（RE= Pr,Nd）content x increasing.The de Gennes factor of Gd（1–x）REx alloy which was associated with the exchange interaction between magnetic spin components also decreased with RE content increasing.The above results showed that the magnetic exchange interaction between magnetic atoms in gadolinium could be effectively changed by the Pr,Nd addition.
