Reduction in the electron density-of-states in superconducting MgB${}_2$ disordered by $n^1$-irradiation: the ${}^{11}$B and ${}^{25}$Mg NMR estimates

Abstract

NMR line shift and nuclear spin-lattice relaxation rate T_1^{-1} of 11B and 25Mg were measured in superconducting MgB_2 (T_c^{ons}=38K) structurally disordered by nuclear reactor neutrons up to the fluence of thermal neutrons $Φ=1 10^{19} cm^{-2}. The temperature of superconducting transition was shifted down to T_{c,irrad}^{ons}=7K under irradiation. The change due irradiation in the partial electron density of states (DOS) at the Fermi energy of boron and magnesium were traced by taking into account that T_1^{-1} of 11B and 25Mg are determined by hyperfine magnetic interactions with carriers. It was revealed that electronic states near E_F of Mg are influenced negligibly by irradiation whereas partial DOS of the B 2p_{x,y} states reduces greatly in irradiated MgB_2. The NMR estimates for DOS using the McMillan formula show that critical temperature decreases in irradiated MgB_2 mainly due to reduction in the partial DOS of p states of boron.

5 pages, 4 figures

References in corpus (5)

• Superconductivity of metallic boron in MgB_2
• Boron Isotope Effect in Superconducting MgB${}_2$
• Superconductivity of MgB2: Covalent Bonds Driven Metallic
• Electronic structure of superconducting MgB2 and related binary and ternary borides
• NMR relaxation rates and Knight shifts in MgB2

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• Superconducting and Normal State Properties of Neutron Irradiated MgB2
• Effect of damage by 2-MeV He ions and annealing on Hc2 in MgB2 thin films
• Point-contact spectroscopy in neutron-irradiated Mg^{11}B_2
• Intraband versus interband scattering rate effects in neutron irradiated MgB2
• ${}^{11}$B and ${}^{27}$Al NMR spin-lattice relaxation and Knight shift study of Mg${}_{1-x}$Al${}_x$B${}_2$. Evidence for anisotropic Fermi surface
• NMR relaxation time in a clean two-band superconductor
• Effect of disorder on the NMR relaxation rate in two-band superconductors
• Superconducting Properties of Atomic-Disordered Compound MgCNi_3