Muon spin rotation study of type-I superconductivity: Elemental β -Sn

Abstract

The application of the muon-spin rotation/relaxation (µSR) technique for studying type-I superconductivity is discussed. In the intermediate state, i.e. when a type-I superconducting sample with non-zero demagnetization factor N is separated into normal state and Meissner state (superconducting) domains, the µSR technique allows to determine with very high precision the value of the thermodynamic critical field Bc, as well as the volume of the sample in the normal and the superconducting state. Due to the microscopic nature of µSR technique, the Bc values are determined directly via measurements of the internal field inside the normal state domains. No assumptions or introduction of any type of measurement criteria are needed.Experiments performed on a 'classical' type-I superconductor, a cylindrically shaped β−Sn sample, allowed to reconstruct the full B − T phase diagram. The zero-temperature value of the thermodynamic critical field Bc(0) = 30.578(6) mT and the transition temperature Tc = 3.717(3) K were determined and found to be in a good agreement with the literature data. An experimentally obtained demagnetization factor is in very good agreement with theoretical calculations of the demagnetization factor of a finite cylinder. The analysis of Bc(T ) dependence within the framework of the phenomenological α−model allow to obtain the value of the superconducting energy gap ∆ = 0.59(1) meV, of the electronic specific heat γe = 1.781(3) mJ/mol K 2 and of the jump in the heat capacity ∆C(Tc)/γTc = 1.55(2).

Type-I superconductivity in the Dirac semimetal PdTe2 probed by μSR

“…Although a powerful technique, µSR on type-I superconductors has not been explored in much detail. Studies of the intermediate state in elemental superconductors are scarce and concise [25][26][27][28][29][30][31] Here we report transverse field muon spin rotation measurements in the superconducting phase of PdTe 2 . Experiments were performed on a thin disk-like crystal in two configurations: (i ) with the field perpendicular to the plane of the disk (N ⊥ = 0.86) and (ii ) with the field in the plane of the disk (N = 0.08).…”

Isotropic s -wave superconductivity in the noncentrosymmetric charge density wave superconductor SrPt2As2

“…To elucidate the nature of the pairing symmetry of the superconducting gap, we tracked the time evolution of the muon-spin polarization P(t ) in the TF configuration of a polycrystalline SrPt 2 As 2 sample. Measurements were done in standard way [45] in the temperature range 0.25 K T 6 K in the presence of a 100-mT magnetic field. In Fig.…”

Isotropic single-gap superconductivity of elemental Pb

“…The transverse-field muon-spin rotation/relaxation (TF-μSR) experiments were conducted using the Dolly spectrometer (π E1 beam line) at the Paul Scherrer Institute, Switzerland. Measurements were performed in the intermediate state of superconducting Pb, i.e., when the sample volume is separated into the normal-state and the superconductingstate (Meissner) domains [15,18,22,[26][27][28][29][30][31][32]. Two sets of experiments were performed.…”

“…The magnetic-field distribution in a type-I superconductor in the intermediate state, which is probed directly by means of TF-μSR, consists of two sharp peaks corresponding to the response of the domains remaining in the Meissner state (B = 0) and in the normal-state (B ≡ B c > B ex ). Consequently, the value of B c could be directly and very precisely determined by measuring the position of the B > B ex peak [18,22,[26][27][28][29][30][31][32][35][36][37][38][39][40]. The details of the TF-μSR experiments on elemental Pb and the data analysis procedure are discussed in the Supplemental Material [41]. )…”