The role of the bridging group in exchange coupling in dinuclear homo- and heterometallic Ni(ii) and Co(ii) complexes with oxalate, oxamidate and dithiooxamidate bridges

2012 ◽  
Vol 41 (37) ◽  
pp. 11319 ◽  
Author(s):  
Elena A. Mikhalyova ◽  
Sergey V. Kolotilov ◽  
Olivier Cador ◽  
Matthias Zeller ◽  
Swiatoslaw Trofimenko ◽  
...  
Keyword(s):  
Exchange Coupling

scholarly journals f-Electron and Magnetic Ordering Effects in Nickelates LaNiO2 and NdNiO2: Remarkable Role of The Cuprate-Like 3dx2-y2 Band

2020 ◽  
Author(s):  
Jianwei Sun ◽  
Ruiqi Zhang ◽  
Christopher Lane ◽  
Bahadur Singh ◽  
Johannes Nokelainen ◽  
...  
Keyword(s):  
Ground State ◽  
Exchange Coupling ◽  
Density Functional ◽  
High Temperature Superconductivity ◽  
Parent Compound ◽  
Magnetic Ordering ◽  
Striking Similarity ◽  
Infinite Layer ◽  
Open Questions

Abstract Recent discovery of superconductivity in the doped infinite-layer nickelates has renewed interest in understanding the nature of high-temperature superconductivity more generally. The low-energy electronic structure of the parent compound NdNiO2, the role of electronic correlations in driving superconductivity, and the possible relationship betweeen the cuprates and the nickelates are still open questions. Here, by comparing LaNiO2 and NdNiO2 systematically within a parameter free density functional framework, all-electron first-principles framework, we reveal the role Nd 4f-electrons in shaping the ground state of pristine NdNiO2. Strong similarities are found between the electronic structures of LaNiO2 and NdNiO2, except for the effects of the 4f-electrons. Hybridization between the Nd 4f and Ni 3d orbitals is shown to significantly modify the Fermi surfaces of various magnetic states. In contrast, the competition between the magnetically ordered phases depends mainly on the gaps in the Ni dx2-y2 band, so that the ground state in LaNiO2 and NdNiO2 turns out to be striking similarity to that of the cuprates. The d - p band-splitting is found to be much larger while the intralayer 3d ion-exchange coupling is smaller in the nickelates compared to the cuprates. Our estimated value of the on-site Hubbard U is similar to that in the cuprates, but the value of the Hund's coupling JH is found to be sensitive to the Nd magnetic moment. The exchange coupling J in NdNiO2 is only half as large as in the curpates, which may explain why Tc in the nickelates is half as large as the cuprates.

scholarly journals THE ROLE OF GRAIN BOUNDARY IN THE Nd2Fe14B/α-Fe EXCHANGE COUPLING MAGNET

2000 ◽  
Vol 49 (11) ◽  
pp. 2281
Author(s):  
JI QI-GEN ◽  
DU YOU-WEI
Keyword(s):  
Grain Boundary ◽  
Exchange Coupling

Studies of Exchange Coupling in Fe/Cu/Fe(001) “Loose Spin” Structures

1995 ◽  
Vol 384 ◽  
Author(s):  
M. Kowalewski ◽  
B. Heinrich ◽  
K. Totland ◽  
J.F. Cochran ◽  
S. Govorkov ◽  
...  
Keyword(s):  
Exchange Coupling ◽  
Interlayer Coupling ◽  
Antiferromagnetic Coupling ◽  
Concentration Limit ◽  
Interlayer Exchange Coupling ◽  
High Concentration ◽  
Significant Difference ◽  
Valence Electrons ◽  
Interlayer Exchange

ABSTRACTThe interlayer exchange coupling has been studied in two trilayer structures:(a) 5.7Fe/5Cu/1FecCu1-c/5Cu/10Fe(001), where c=0.0, 0.1, 0.2, 0.45 0.60(b) 5.7Fe/5Cu/1CrcCu1-c/5Cu/10Fe(001), where c=0.1, 0.45, 0.8 and 1.0.The intention of these studies was to identify the role of Fe and Cr atoms in the alloyed FecCu1-c and CrcCu1-c layers on the direct interlayer coupling which is facilitated by the Cu valence electrons. FMR, BLS and MOKE studies were used to determine the interlayer exchange coupling. Mossbauer spectroscopy was used to identify the magnetic state of the Fe atoms in the alloyed layer. The results showed that the presence of foreign atoms inside the Cu spacer significantly decreased the bilinear antiferromagnetic coupling between the Fe layers. In the low concentration limit the Fe and Cr atoms behaved in a similar manner. A significant difference was found in the high concentration limit where the Fe atoms start to be partially magnetically ordered.

scholarly journals Exchange coupling between silicon donors: The crucial role of the central cell and mass anisotropy

2014 ◽  
Vol 89 (23) ◽  
Author(s):  
G. Pica ◽  
B. W. Lovett ◽  
R. N. Bhatt ◽  
S. A. Lyon
Keyword(s):  
Crucial Role ◽  
Exchange Coupling ◽  
Central Cell

SUPERCONDUCTIVITY AND FERROMAGNETISM IN HYBRID SYSTEMS

2003 ◽  
Vol 17 (04n06) ◽  
pp. 661-667
Author(s):  
MARIO CUOCO ◽  
CANIO NOCE
Keyword(s):  
Phase Diagram ◽  
Charge Transfer ◽  
Single Particle ◽  
Normal State ◽  
Exchange Coupling ◽  
Spin Exchange ◽  
Critical Value ◽  
Particle Charge ◽  
Spin Singlet

Interplay of superconductivity (SC) and ferromagnetism (FM) is studied in a system constituted of alternated planes with FM metallicity and spin singlet SC, respectively. The phase diagram of the SC, FM, and normal state is obtained as the amplitude of the single particle charge transfer between the planes is varied. One important finding is the appearance of a region with coexistence of SC and FM at small values of the interlayer hopping amplitude, though the FM exchange coupling is below the critical value indicated by the Stoner criterium. We consider the role of the direct spin exchange coupling with respect to the degree of hybridization between FM and SC fermions and how those mechanisms may destroy the coexisting phase. Relation to exotic superconductors recently discovered, as the ruthenate-cuprate compound of the class RuSr 2 GdCu 2 O 8, is also presented.

Role of diffused Co atoms in improving effective exchange coupling inSm−Co∕Fespring magnets

2007 ◽  
Vol 75 (10) ◽  
Author(s):  
Y. Choi ◽  
J. S. Jiang ◽  
Y. Ding ◽  
R. A. Rosenberg ◽  
J. E. Pearson ◽  
...  
Keyword(s):  
Exchange Coupling ◽  
Effective Exchange
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