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Title: Evidence for strong enhancement of the magnetic ordering temperature of trivalent Nd metal under extreme pressure

Abstract

Four-point electrical resistivity measurements were carried out on Nd metal and dilute magnetic alloys containing up to 1 at.% Nd in superconducting Y for temperatures 1.5-295 K under pressures to 210 GPa. The magnetic ordering temperature To of Nd appears to rise steeply under pressure, increasing ninefold to 180 K at 70 GPa before falling rapidly. Y( Nd) alloys display both a resistivity minimum and superconducting pair breaking Delta T-c as large as 38 K/at.% Nd. The present results give evidence that for pressures above 30-40 GPa, the exchange coupling J between Nd ions and conduction electrons becomes negative, thus activating Kondo physics in this highly correlated electron system. The rise and fall of T-o and Delta T-c with pressure can be accounted for in terms of an increase in the Kondo temperature.

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF); Carnegie/DOE Alliance Center (CDAC); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1433007
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 95; Journal Issue: 20
Country of Publication:
United States
Language:
English

Citation Formats

Song, J., Bi, W., Haskel, D., and Schilling, J. S.. Evidence for strong enhancement of the magnetic ordering temperature of trivalent Nd metal under extreme pressure. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.95.205138.
Song, J., Bi, W., Haskel, D., & Schilling, J. S.. Evidence for strong enhancement of the magnetic ordering temperature of trivalent Nd metal under extreme pressure. United States. doi:10.1103/PhysRevB.95.205138.
Song, J., Bi, W., Haskel, D., and Schilling, J. S.. Mon . "Evidence for strong enhancement of the magnetic ordering temperature of trivalent Nd metal under extreme pressure". United States. doi:10.1103/PhysRevB.95.205138.
@article{osti_1433007,
title = {Evidence for strong enhancement of the magnetic ordering temperature of trivalent Nd metal under extreme pressure},
author = {Song, J. and Bi, W. and Haskel, D. and Schilling, J. S.},
abstractNote = {Four-point electrical resistivity measurements were carried out on Nd metal and dilute magnetic alloys containing up to 1 at.% Nd in superconducting Y for temperatures 1.5-295 K under pressures to 210 GPa. The magnetic ordering temperature To of Nd appears to rise steeply under pressure, increasing ninefold to 180 K at 70 GPa before falling rapidly. Y( Nd) alloys display both a resistivity minimum and superconducting pair breaking Delta T-c as large as 38 K/at.% Nd. The present results give evidence that for pressures above 30-40 GPa, the exchange coupling J between Nd ions and conduction electrons becomes negative, thus activating Kondo physics in this highly correlated electron system. The rise and fall of T-o and Delta T-c with pressure can be accounted for in terms of an increase in the Kondo temperature.},
doi = {10.1103/PhysRevB.95.205138},
journal = {Physical Review B},
number = 20,
volume = 95,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}
  • Four-point electrical resistivity measurements were carried out on Nd metal and dilute magnetic alloys containing up to 1 at.% Nd in superconducting Y for temperatures 1.5–295 K under pressures to 210 GPa. The magnetic ordering temperature T o of Nd appears to rise steeply under pressure, increasing ninefold to 180 K at 70 GPa before falling rapidly. Y(Nd) alloys display both a resistivity minimum and superconducting pair breaking ΔT c as large as 38 K/at.% Nd. The present results give evidence that for pressures above 30–40 GPa, the exchange coupling J between Nd ions and conduction electrons becomes negative, thusmore » activating Kondo physics in this highly correlated electron system. Furthermore, the rise and fall of T o and ΔT c with pressure can be accounted for in terms of an increase in the Kondo temperature.« less
  • Today's best permanent magnet materials, SmCo 5 and Nd 2Fe 14B, could likely be made signi fi cantly more powerful were it not necessary to dilute the strong magnetism of the rare earth ions (Sm, Nd) with the 3 d transition elements (Fe, Co). Since the rare-earth metals order magnetically at relatively low temperatures T o <= 292 K, transition elements must be added to bring T o to temperatures well above ambient. Under pressure T o (P) for the neighboring lanthanides Gd, Tb, and Dy follows a notably nonmonotonic, but nearly identical, dependence to similar to 60 GPa. Atmore » higher pressures, however, Tb and Dy exhibit highly anomalous behavior, T o for Dy soaring to temperatures well above ambient. In conclusion, we suggest that this anomalously high magnetic ordering temperature is an heretofore unrecognized feature of the Kondo lattice state.« less
  • Ln{sub 2}YbCuQ{sub 5} (Ln = La, Ce, Pr, Nd, Sm; Q = S, Se) have been prepared by direct reaction of the elements in Sb{sub 2}Q{sub 3} (Q = S, Se) fluxes at 900 °C. All compounds have been characterized by single-crystal X-ray diffraction methods and they are isotypic. The structure of Ln{sub 2}YbCuQ{sub 5} consists of one-dimensional {sup 1}{sub {infinity}} [YbCuQ{sub 5}]{sup 6-} ribbons extending along the b axis that are connected by larger Ln{sup 3+} ions. Each ribbon is constructed from two single chains of [YbQ{sub 6}] octahedra with one double chain of [CuQ{sub 5}] trigonal bipyramids inmore » the middle. All three chains connect with each other via edge-sharing. There are two crystallographically unique Ln atoms, one octahedral Yb site, and two disordered Cu positions inside of distorted Q{sub 5} trigonal bipyramids. Both Ln atoms are surrounded by eight Q atoms in bicapped trigonal prisms. The magnetic properties of Ln{sub 2}YbCuQ{sub 5} have been characterized using magnetic susceptibility and heat capacity measurements, while their optical properties have been explored using UV-vis-NIR diffuse reflectance spectroscopy. Cesub 2}YbCuSe{sub 5}, La{sub 2}YbCuS{sub 5}, Ce{sub 2}YbCuS{sub 5}, and Pr{sub 2}YbCuS{sub 5} are Curie-Weiss paramagnets. La{sub 2}YbCuSe{sub 5} and Nd{sub 2}YbCuS{sub 5} show evidence for short-range antiferromagnetic ordering at low temperatures. Sm{sub 2}YbCuS{sub 5} shows magnetic ordering at 5.9 K, followed by negative magnetization at low external fields. The band gaps of La{sub 2}YbCuSe{sub 5}, Ce{sub 2}YbCuSe{sub 5}, La{sub 2}YbCuS{sub 5}, Ce{sub 2}YbCuS{sub 5}, Pr{sub 2}YbCuS{sub 5}, Nd{sub 2}YbCuS{sub 5},and Sm{sub 2}YbCuS{sub 5} are 1.15 eV, 1.05 eV, 1.45 eV, 1.37 eV, 1.25 eV, 1.35 eV, and 1.28 eV respectively.« less
  • The structures of the perovskites Nd{sub 0.7}Ca{sub 0.30-x}Sr{sub x}MnO{sub 3} have been determined at 293 and 1.7 K for x = 0, 0.08, and 0.3. All these manganites, except the low-temperature form of Nd{sub 0.7}Ca{sub 0.3}MnO{sub 3} (x=0), exhibit the classical orthorhombic Pnma (GdFeO{sub 3}) structure. For Nd{sub 0.7}Ca{sub 0.3}MnO{sub 3}, a monoclinic structure, involving a new kind of charge ordering, is observed at 1.7 K. The importance of this phenomenon for the understanding of the CMR properties of these materials is emphasized.