General Introduction

Our group maintains and actively develops a full suit of µSR instruments making use of positive muons with impulses ranging from 28 to 110 MeV/c. Such muons allow scientists to research a wide range of fundamental questions in the field of condensed matter physics or chemistry.

Our group is reponsible for 5 instruments. DOLLY, GPD, GPS and LTF are presently open to users, whereas our new HAL-9500 (High-field And Low temperatures MuSR instrument) will be open gradually starting in 2014.

The demand for our instruments is huge with overbooking factors up to 4 for the piM3 beamline (where GPS and LTF are located). In 2012, 146 research proposals of groups from PSI, Swiss universities and from abroad have been active on the bulk µSR instruments.

The main topics studied with our instruments are:

• Novel superconductors: MuSR studies can provide information for example on the symmetry of the superconducting gap; topology of the Abrikosov state; interplay with magnetism; inhomogeneity of the superconducting state.
• Magnetism: Here the main topics investigated are frustrations and spin ice; low dimensional spin systems; interplay with other states as superconductivity; inhomogeneous magnetism; spin glass states.

The instruments for bulk µSR studies have the following characteristics:

• DOLLY: General Purpose Surface Muon Instrument; Muon energy: 4.2 MeV; Temperatures: 1.6 – 300 K; Magnetic fields: 0 – 0.5 T
• GPD: General Purpose Decay Channel Instrument; Muon energy: 5 – 60 MeV; Temperatures: 0.3 – 500 K; Magnetic Fields: 0 – 0.5 T
• GPS: General Purpose Surface Muon Instrument; Muon energy: 4.2 MeV; Temperatures: 1.6 – 1200 K; Magnetic fields: 0 – 0.54 T; Muons on Request (MORE)
• LTF: Low Temperature Facility; Muon energy: 4.2 MeV; Temperatures: 0.02 mK – 4.2 K; Magnetic fields: 0 – 3 T; Muons on Request (MORE)
• HAL-9500: The new High-Fiel µSR Instrument is equipped with a 9.5 T magnet and sample environments to reach 0.01 K up to 300 K.