| AVS 64th International Symposium & Exhibition | |
| Actinides and Rare Earths Focus Topic | Monday Sessions |
| Session AC+MI+SA+SU-MoM |
| Session: | Magnetism, Complexity, and Superconductivity in the Actinides and Rare Earths |
| Presenter: | Attila Bartha, Charles University, Prague, Czech Republic |
| Authors: | A. Bartha, Charles University, Prague, Czech Republic M. Klicpera, Charles University, Prague, Czech Republic P. Čermák, Forschungszentrum Juelich GmbH, Germany B. Ouladdiaf, Institut Laue Langevin, France P. Javorský, Charles University, Prague, Czech Republic J. Custers, Charles University, Prague, Czech Republic |
| Correspondent: | Click to Email |
Materials of reduced dimensionality appear in many contemporary fields of research and technology, because they encompass a wide variety of interesting electronic phenomena. For instance carbon can be prepared in 3D (diamond), quasi-2D (graphite), 2D (graphene) or 1D (carbon nanotubes). All of these structures have distinct electronics. Diamond is an insulator. Graphene is semimetal. However, when the dimensionality is increased by putting several graphene layers together (eventually making graphite), the resulting band structure moves to that of a more trivial metal. Another example is high temperature superconductors being quasi-2D materials as well.
The role of dimensionality in f-electron systems has been mainly discussed in the context of quantum phase transitions and related phenomena. The series CenTmIn3n+2m(n=1, 2; m=0, 1, 2; T=transition metal) of layered compounds, which can be viewed as m TIn2–layers alternating with n–layers of CeIn3 along the c-axis, has been extensively investigated. CeIn3 is cubic (3D) and orders antiferromagnetically (AFM) at TN = 10.2 K [1] with a propagation vector k = (0.5, 0.5, 0.5) [2]. Under hydrostatic pressure superconductivity appears with highest Tc = 0.3 K at p = 2.5 GPa. In CeRhIn5, the anisotropic crystal structure leads to an incommensurate magnetic structure described with k = (0.5, 0.5, 0.297). The AFM order is reduced (TN = 3.8 K) while superconductivity is supported, Tc increases to 1.9 K at p = 1.77 GPa [3-4].
We report on the magnetic structures of URhIn5 and U2RhIn8, two new members of this intriguing RnTmX3n+2m(R= Lanthanide, Actinide, X = In, Ga) family of compounds. Neutron diffraction measurements were performed on structurally well-defined single crystals. Both, URhIn5 and U2RhIn8, adopt the tetragonal HonCoGa3n+2-type structure (P4/mmm) typical for this group of compounds. URhIn5 orders antiferromagnetically below TN = 98 K. The propagation vector equals k = (0.5, 0.5, 0.5) and we obtained a value of 1.65 µB/U3+ for the size of the ordered magnetic moment. The antiferromagnetic transition temperature of U2RhIn8 is higher yielding 117 K. We found that the magnetic structure can be described by propagation vector k = (0.5, 0.5, 0). The respective ordered magnetic moment amounts 1.7 µB/U3+. In both materials the ordered magnetic moments are aligned along the tetragonal c-axis. Comparison with isostructural compounds and general conclusions for the series will be presented.
[1] C. Pfleiderer, Rev. Mod. Phys. 81 (2009) 1551
[2] A Benoit et al., Solid State Commun. 34 (1980) 39
[3] H. Shishido et al. J. Phys. Soc. Jpn. Vol. 71 Suppl. (2002) 276
[4] H. Hegger et al., Phys. Rev. Lett. 84 (2000) 4986