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Quasiparticle Excitations outside the Vortex Cores in MgB$_2$ Probed by Muon Spin Rotation

Kazuki Ohishi·Takahiro Muranaka·Jun Akimitsu·Akihiro Koda·Wataru Higemoto·Ryosuke Kadono
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Abstract

The magnetic penetration depth $λ$ in the mixed state of MgB$_2$ has been determined microscopically from the field distribution around magnetic vortices probed by muon spin rotation. Both the temperature and magnetic field dependence of $λ$ strongly suggest the presence of delocalized quasiparticles around the vortex cores. In particular, the effect of Doppler shift has been clearly observed as a finite gradient of the field dependence of $λ$, strongly suggesting an anisotropic order parameter with the region of a vanishingly small energy gap.

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Kazuki Ohishi, Takahiro Muranaka, Jun Akimitsu, Akihiro Koda, Wataru Higemoto, Ryosuke Kadono. 2002-12-02. Quasiparticle Excitations outside the Vortex Cores in MgB$_2$ Probed by Muon Spin Rotation. https://doi.org/10.1143/jpsj.72.29

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