Mott transition in granular aluminum

Abstract

The presence of free spins in granular Al films is directly demonstrated by $\mu$SR measurements. A Mott transition is observed by probing the increase of the spin-flip scattering rate of conduction electrons as the nano-size metallic grains are being progressively decoupled. Analysis of the magneto-resistance in terms of an effective Fermi energy shows that it becomes of the order of the grains electrostatic charging energy at a room temperature resistivity $\rho \approx 50,000\mu \Omega cm$, at which a metal to insulator transition is known to exist. As this transition is approached the magneto-resistance exhibits a Heavy-Fermion like behavior, consistent with an increased electron effective mass.

5 pages, 3 figures

References in corpus (3)

• Magnetism in SQUIDs at Millikelvin Temperatures
• Microscopic origin of low frequency flux noise in Josephson circuits
• Spin-like susceptibility of metallic and insulating thin films at low temperature

Cited by in corpus (2)

• Electrodynamics of granular aluminum from superconductor to insulator: observation of collective superconducting modes
• Optical conductivity of granular aluminum films near the Mott metal-to-insulator transition