Lingjia Shen

Position:

PhD Student - Li Siguang Scholar

Research Topics:

Spin structure in magnetic materials

Magnetic field induced phase transitions

Superconductors

Group:

Large facilities research

Introduction:

My name is Lingjia Shen, currently a second year PhD in the group under the supervision of Dr Elizabeth Blackburn. My main research area is the study of magnetic order in frustrated systems. In general, I use two ways to frustrate the spin orientations in strong correlated systems. One way is to make use of some special geometric arrangements such as triangles and tetrahedrons. Another way is to create systems with multiple exchange interactions, so that different ordered states are able to coexist in one system. I am familiar with making samples by solid state reaction, high vacuum arc-melting and sol-gel methods. I use lab-based facilities (e.g. XRD, MPMS, VSM) to do a first-stage characterization. Then if the sample shows promising properties, we move to large facilities to have a deeper look. Besides novel magnetism, I am also partly involved in several training programmes studying vortex lattices in superconductors.

Recent work:

For example, I am studying the magnetic avalanches in the time-honoured manganites with ABO3 structure. Magnetic avalanche-like metamagnetism (MM) is very popular in this kind of systems below a critical temperature (Fig. 1). The sample undergoes several ultra-sharp steps in magnetization when applied by a magnetic field. These steps have a quite distinguished feature from other MM ever reported.

Figure 1: Typical magnetization as a function of field for an avalanche-like metamagnet.



Because of the phase separation seen in these manganites, small angle neutron scattering (SANS) is a very powerful tool to study them. However, due to the high field needed to fully magnetize the sample, the high field MM branch, which is actually very important for understanding the nature of these steps, had not been previously been. Recently we carried out a detailed SANS measurement on it in fields up to 16.5 T using our 17-tesla magnet (Fig. 2)!

Figure 2: Example of magnetic SANS data collected at FRM-II, Munich. The plot was generated using the GRASP software program.



The data analysis is still in progress. We hope we can develop more fundamental ideas about these avalanches in future!

If you have any interest on related areas, you are more than welcome to discuss them with me!

Recent and Approaching Conferences:

Recent activities:

E-mail:

Tel: +44 (0) 121 415 8254
Fax: +44 (0) 121 414 8277
Room: East 213