Low-field cross spin relaxation ofL8iin superconductingNbSe2

Abstract

A low energy beam of spin polarized 8 Li has been used to investigate nuclear spin relaxation in the multiband superconductor NbSe 2 . In low magnetic fields there is significant cross relaxation between the 8 Li and the host 93 Nb spins, which is driven by low frequency fluctuations in the nuclear magnetic dipolar interaction. The rate of cross relaxation is strongly field dependent and thus the 1 / T 1 spin relaxation rate of the 8 Li is a sensitive monitor of the static local magnetic field B just below the surface. This in turn is used to determine the absolute value of the magnetic penetration depth in the Meissner state. The temperature variations in 1 / T 1 and are consistent with a wide distribution of superconducting gaps expected for a multiband superconductor.

Slow order-parameter fluctuations in superconducting Pb and Ag/Nb films observed usingβ-detected nuclear magnetic resonance

“…The interaction produces a significant cross relaxation between 8 Li and 207 Pb nuclear spins in low field where the Larmor frequencies of the 207 Pb and 8 Li are small and thus nearly equal. As shown in [17] this process characteristically gives rise to a strong Lorentzian field dependent 1 T1 evident in the normal state in Fig. 2(a),(b).…”

Signatures of new d-wave vortex physics in overdoped Tl2Ba2CuO6+x revealed by TF-µ+SR

“…First, however, the details and origin of the exotic temperature dependence must be conclusively confirmed. Sensitive scanning probe microscopies may provide insights into the current and quasiparticle distribution in the vortex cores, while confirmation that this is a vortex state phenomenon awaits Meissner-state field distribution measurements, such as low-energy µSR [44] or β-NMR [45]. The regimes in which these d-wave vortices manifest their unique d-wave physics may provide crucial new insight on the cuprates' order parameter and still-mysterious pairing.…”

Detection and decoherence of level-crossing resonances of8Li in Cu

“…The current study establishes that the site of implanted 8 Li can be determined via its level crossing resonances and therefore has important applications in experiments where the 8 Li is being used as a local probe of bulk materials, ultrathin films, and interfaces. [13][14][15][16][17][18][19][20][21][22] The resonances are detectable as an enhancement in the 8 Li 1/T 1 due to cross relaxation with the neighboring Cu spins. The large width of the resonances is attributed to fluctuations in the surrounding nuclear spin bath, which are treated using a simple strong collision model.…”

“…14 There is also an overall increase in 1/T 1 as B is decreased toward zero. This is due to many unresolved level crossings near zero field 14,19 and does not provide spectroscopic information on the 8 Li. The interest in this paper lies in the pronounced enhancements in 1/T 1 at specific magnetic fields, which are attributed to resolved level crossings in the 8 Li-Cu subsystem.…”