A magnetization and ${}^{11}$B NMR study of Mg${}_{1-x}$Al${}_x$B${}_2$ superconductors

Abstract

We demonstrate for the first time the magnetic field distribution of the pure vortex state in lightly doped Mg${}_{1-x}$Al${}_x$B${}_2$ ($x\le 0.025$) powder samples, by using ${}^{11}$B NMR in magnetic fields of 23.5 and 47 kOe. The magnetic field distribution at T=5 K is Al-doping dependent, revealing a considerable decrease of anisotropy in respect to pure MgB${}_2$. This result correlates nicely with magnetization measurements and is consistent with $\sigma$-band hole driven superconductivity for MgB${}_2$.

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Cited by in corpus (6)

• Carbon-substitution effect on the electronic properties of MgB${}_2$ single crystals
• Peak effect in single crystal MgB${}_2$ superconductor for $\mathbf{H}\parallel c$-axis
• Anisotropy parameters of superconducting MgB${}_2$
• High-pressure synthesis of pure and doped superconducting MgB2 compounds
• ${}^{11}$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
• ${}^{11}$B NMR study of pure and lightly carbon doped MgB${}_2$ superconductors