Magnetization dynamics and frustration in the multiferroic double perovskite Lu2MnCoO6

We investigate the magnetic ordering and the magnetization dynamics (from kHz to THz time scales) of the double perovskite Lu2MnCoO6 using elastic neutron diffraction, muon spin relaxation, and micro-Hall magnetization measurements. This compound is known to be a type II multiferroic with the interesting feature that a ferromagneticlike magnetization hysteresis loop couples to an equally hysteretic electric polarization in the bulk of the material despite a zero-field magnetic ordering of the type ↑↑↓↓ along Co-Mn spin chains. Here we explore the unusual dynamics of this compound and find extremely strong fluctuations, consistent with the axial next-nearest-neighbor Ising (ANNNI) model for frustrated spin chains. We identify three temperature scales in Lu2MnCoO6 corresponding to the onset of highly fluctuating long-range order below TN=50±3 K identified from neutron scattering, the onset of magnetic and electric hysteresis, with change in kHz magnetic and electric dynamics below a 30 K temperature scale, and partial freezing of ∼MHz spin fluctuations in the muon spin relaxation data below 12±3 K. Our results provide a framework for understanding the multiferroic behavior of this compound and its hysteresis and dynamics

The representation and attainment of students with a visual impairment in higher education

We carried out an analysis of a database of all students in higher education in the UK in 1995-96 to compare students with a visual impairment and students with no recorded disability in terms of their demographic characteristics, programmes of study and academic attainment. Students with a visual impairment constituted 0.12% of all students normally resident in the UK. Their representation varied with age, gender, ethnicity and entry qualifications and with their level, mode and subject of study. If these background variables are taken into account, a visual impairment per se appears to have surprisingly little effect on academic attainment