Valence and magnetic instabilities in Sm compounds at high pressures

Abstract

We report on the study of the response to high pressures of the electronic and magnetic properties of several Sm-based compounds, which span at ambient pressure the whole range of stable charge states between the divalent and the trivalent. Our nuclear forward scattering of synchrotron radiation and specific heat investigations show that in both golden SmS and SmB 6 the pressure-induced insulator to metal transitions (at 2 and ∼ 4 -7 GPa, respectively) are associated with the onset of long-range magnetic order, stable up to at least 19 and 26 GPa, respectively. This long-range magnetic order, which is characteristic of Sm 3+ , appears already for a Sm valence near 2.7. Contrary to these compounds, metallic Sm, which is trivalent at ambient pressure, undergoes a series of pressure-induced structural phase transitions which are associated with a progressive decrease of the ordered 4f moment.

Geophysical applications of nuclear resonant spectroscopy

“…The measurement and analysis of such time spectra constitute the main part of the SMS method. Dur ing the last decade, we saw the refinement of the SMS technique and its application in the area of high-pressure research (Nasu, 1994(Nasu, , 1998Zhang et al, 1999;Pleines et al, 1999;Lubbers et al, 1999b;Lin et al, 2004a;Barla et al, 2004aBarla et al, , 2004bBarla et al, , 2005aBarla et al, , 2005bJackson et al, 2005a).…”

“…The straight line indicates identical temperatures. 57Fe isotope (Nasu, 1998;Lubbers et aL, 1999aLubbers et aL, , 1999bLubbers et aL, , 2000bRupprecht et aL, 2000;Wortmann et al, 2002;Lin et aL, 2004a;Mao et al, 2004b), the l5lEu isotope (Lubbers et al, 1999a;Lengsdorf et al, 2004), the 119Sn isotope (Barla et al, 2005a), and the 149Sm isotope (Barla et aL, 2004a(Barla et aL, , 2004b(Barla et aL, , 2005b. Geophysi cal applications of the SMS method examined the pressure dependence of magnetism in materials like Fe3S (Lin et aL, 2004a) or FeH^ .…”

Lattice dynamics of the rare-earth element samarium

“…These values are consistent with the published data for Sm-type structured metallic Sm at this temperature. 35 The polycrystalline Sm foil has also been characterized by temperature-dependent nuclear forward scattering. Figure 3 plots selected spectra measured at transmission geometry and at various temperatures.…”

Magnetic and Electronic Transition in Samarium Chalcogenides

“…The magnetic transition [(SmX,X=S,Se and Te)] have occurred pseudo-gap in the metallic state and reveled paramagnetic behavior. It has shown the non-magnetic semiconducting state due to different lattice behavior and discontinuous transition at 6.5kbar [5][6][7].…”