On the edge of periodicity: Unconventional magnetism of Gd117Co56.4Sn114.3

Abstract

Magnetization measurements reveal the onset of magnetic ordering at TC = 65 K followed by three additional magnetic anomalies at T1 = 47 K, T2 = 28 K, and T3 = 11 K in Gd117Co56.4Sn114.3 -a compound with a giant cubic unit cell that crystallizes in the Dy117Co56Sn112 structure type with space group Fm3¯m and lattice parameter a = 30.186 Å. The magnetic ordering temperature increases with applied magnetic field; however, the analysis of magnetic data indicates that antiferromagnetic interactions also play a role in the ground state. AC magnetic susceptibility confirms multiple magnetic anomalies and shows minor frequency dependence. The local magnetic ordering below 60 K is supported by the Mössbauer spectroscopy. A single broad anomaly is detected at T3 in the heat capacity; we suggest that magnetic domains form below this temperature. These data highlight unique features of magnetism in this and, potentially, other rare-earth intermetallics crystallizing with giant unit-cells where the exchange correlation lengths are much shorter when compared to the periodicity of the crystal lattice. AbstractMagnetization measurements reveal the onset of magnetic ordering at T C = 65 K followed by three additional magnetic anomalies at T 1 = 47 K, T 2 = 28 K, and T 3 = 11 K in Gd 117 Co 56.4 Sn 114.3 -a compound with a giant cubic unit cell that crystallizes in the Dy 117 Co 56 Sn 112 structure type with space group 3 � and lattice parameter a = 30.186 Å. The magnetic ordering temperature increases with applied magnetic field; however, the analysis of magnetic data indicates that antiferromagnetic interactions also play a role in the ground state. AC magnetic susceptibility confirms multiple magnetic anomalies and shows minor frequency dependence. The local magnetic ordering below 60 K is supported by the Mössbauer spectroscopy. A single broad anomaly is detected at T 3 in the heat capacity; we suggest that magnetic domains form below this temperature. These data highlight unique features of magnetism in this and, potentially, other rare-earth intermetallics crystallizing with giant unit-cells where the exchange correlation lengths are much shorter when compared to the periodicity of the crystal lattice.

Structure and Oxidation States of Giant Unit Cell Compound Dy117+xFe57–ySn112–z

“…Electron-dispersive X-ray spectroscopy was conducted using a Zeiss LEO model 1530 variable-pressure field effect scanning with an EDX ARTICLE attachment. Operating at an acceleration voltage of 19 kV, the spectra was integrated for 30 s. To directly compare the composition of the compound with other analogues of the structure type, the Dy concentration was set to 117 leading to the composition of Dy 117 (13) Fe 56(6) Sn 137 (9) . Based on six different measurements on the same single crystal, we note the higher Sn concentration is due to excess Sn on the surface.…”

“…In a more recent report of the R 117 Co 52+ Sn 112+γ (R = Y, La, Pr, Nd, Ho) analogues, all magnetic lanthanide elements display local magnetism, while Y 117 Co 56 Sn 115 manifests weak paramagnetism [12] with a magnetic moment of 1.62 μ B /Co atom. Because of the magnetic [13] and electrical properties discovered in this struc-fully occupied atomic positions, three unique pairs of alternating atomic positions with positional disorder, and seven partially occupied atomic sites. Within this complex unit cell, only approximately half the unique atomic positions are fully occupied with the remainder of the atoms either positionally or occupationally disordered.…”

“…In a more recent report of the R 117 Co 52+ẟ Sn 112+ γ ( R = Y, La, Pr, Nd, Ho) analogues, all magnetic lanthanide elements display local magnetism, while Y 117 Co 56 Sn 115 manifests weak paramagnetism with a magnetic moment of 1.62 μ B /Co atom. Because of the magnetic and electrical properties discovered in this structure type, such as spin reorientation, spin glass behavior, and low lattice thermal conductivity (for Gd 117 Co 56 Sn 112 , κ L = 0.28 W · m –1 · K –1 ), we were motivated to grow single crystals suitable for determining the magnetic properties in a new Fe‐based analogue. Herein, we report the crystal structure and X‐ray photoelectron spectroscopy of Dy 122 Fe 55 Sn 101 .…”

“…Interestingly, the giant unit cells crystal structures can be simplified by viewing the polyhedra as a face‐centered cubic skeleton . Shatruk et al have beautifully summarized the structure of compounds adopting the Dy 117 Co 57 Sn 112 structure type via a nested polyhedral description and several research groups have investigated both the structure and magnetism . Special emphasis is placed on the synthesis of these intermetallics due to their large unit cells (up to ca.…”

“…[2] Shatruk et al have beautifully summarized the structure of compounds adopting the Dy 117 Co 57 Sn 112 structure type via a nested polyhedral description [1][2][3][4][5][6][7] and several research groups have investigated both the structure and magnetism. [8][9][10][11][12][13] Special emphasis is placed on the synthesis of these intermetallics due to their large unit cells (up to ca. 27,000 Å 3 ) and structural complexity.…”