Substitution effect on the superconductivity in Mo_(3-x)Re_xAl_(2)C withβ-Mn structure prepared by microwave method

We report the microwave synthesis and the doping effect of Mo_(3-)xRe_xAl_(2)C(0≤x≤0.3)superconductor.Re doping into Mo_(3)Al_(2)C results in a regular shrinkage of the lattice,marked by the linear decrease of lattice parameter a from6.868(1)A(for Mo_(3)Al_(2)C)to 6.846(2)A(for Mo_(2.7)Re_(0.3)Al_(2)C).Upon Re doping,T_(c)of Mo_(3-x)Re_xAl_(2)C first increases and then decreases,with the maximum T_(c)=9.14 K at the optimal doping level of x=0.09.Our report provides a convenient method to synthesize Mo_(3-)xRe_xAl_(2)C within minutes,and also marks the first Re doping study with enhanced superconductivity on the non-centrosymmetric superconductor Mo_(3)Al_(2)C.

Strong-coupling superconductivity with T_(c)~10.8 K induced by P doping in the topological semimetal Mo_(5)Si_(3)

By performing P doping on the Si sites in the topological semimetal Mo_(5)Si_(3),we discover strong-coupling superconductivity in Mo_(5)Si_(3-x)P_(x)(0.5≤x≤2.0).Mo_(5)Si_(3)crystallizes in the W_(5)Si_(3)-type structure with space group of I4/mcm(No.140),and is not a superconductor itself.Upon P doping,the lattice parameter a decreases while c increases monotonously.Bulk superconductivity is revealed in Mo_(5)Si_(3-x)P_(x)(0.5≤x≤2.0)from resistivity,magnetization,and heat capacity measurements.T_(c)in Mo_(5)Si_(1.5)P_(1.5)reaches as high as 10.8 K,setting a new record among the W_(5)Si_(3)-type superconductors.The upper and lower critical fields for Mo_(5)Si_(1.5)P_(1.5)are 14.56 T and 105 mT,respectively.Moreover,Mo_(5)Si_(1.5)P_(1.5)is found to be a fully gapped superconductor with strong electron-phonon coupling.First-principles calculations suggest that the enhancement of electron-phonon coupling is possibly due to the shift of the Fermi level,which is induced by electron doping.The calculations also reveal the nontrivial band topology in Mo_(5)Si_(3).The T_(c)and upper critical field in Mo_(5)Si_(3-x)P_(x) are fairly high among pseudobinary compounds.Both of them are higher than those in NbTi,making future applications promising.Our results suggest that the W_(5)Si_(3)-type compounds are ideal platforms to search for new superconductors.By examinations of their band topologies,more candidates for topological superconductors can be expected in this structural family.