Thomas Prokscha

Magnetic phase diagram of low-doped La2-xSrxCuO4 thin films studied by low-energy muon-spin rotation

The magnetic phase diagram of La2-xSrxCuO4 thin films grown on single-crystal LaSrAlO4 substrates has been determined by low-energy muon-spin rotation. The diagram shows the same features as the one of bulk La2-xSrxCuO4, but the transition temperatures between distinct magnetic states are significantly different. In the antiferromagnetic phase the Neel temperature T-N is strongly reduced, and no hole spin freezing is observed at low temperatures. In the disordered magnetic phase (x greater than or similar to 0.02) the transition temperature to the cluster spin-glass state T-g is enhanced. Possible reasons for the pronounced differences between the magnetic phase diagrams of thin-film and bulk samples are discussed.

Improved upper limit on muonium to antimuonium conversion

A new experiment has been set up at the Paul Scherrer Institut to search for muonium to antimuonium conversion. No event was found to fulfil the requested signature which consists of the coincident detection of both constituents of the antiatom in its decay. Assuming an effective (V - A) x (V - A) type interaction an improved upper limit is established for the conversion probability of P() less than or equal to 8 x 10(-9) (90% C.L.), which is almost 2 orders of magnitude lower compared to previous results and provides a sensitive test for theoretical extensions of the standard model.

Absence of spontaneous magnetism associated with a possible time-reversal symmetry breaking state beneath the surface of (110)-oriented YBa2Cu3O7−δsuperconducting films

We report the results of a search for spontaneous magnetism due to a time reversal symmetry breaking phase in the superconducting state of (110)-oriented YBa2Cu3O7−δ films, expected near the surface in this geometry. Zero field and weak transverse field measurements performed using the low-energy muon spin rotation technique with muons implanted few nm inside optimally-doped YBa2Cu3O7−δ-(110) films show no appearance of spontaneous magnetic fields below the superconducting temperature down to 2.9 K. Our results give an upper limit of ∼0.02 mT for putative spontaneous internal fields.

Modifications of the Meissner screening profile in YBa2Cu3O7−δthin films by gold nanoparticles

Adding Au nanoparticles to YBa

Development of a very low energy μ+ beam at PSI

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Low-energy muons at PSI: examples of investigations of superconducting properties in near-surface regions and heterostuctures

Cu

Depth dependence of the ionization energy of shallow hydrogen states in ZnO and CdS

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A low energy muon spin rotation and point contact tunneling study of niobium films prepared for superconducting cavities

O

Data underpinning: Remotely induced magnetism in a normal metal using a superconducting spin-valve

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Two-Dimensional Magnetic and Superconducting Phases in Metal-Insulator La2−xSrxCuO4 Superlattices Studied by Low-Energy Muon-Spin Rotation

thin films leads to an increase of the superconducting transition temperature