Understanding Magnetic Exchange in Molecule-Based Magnets from an Electronic Structure Point of View

2015 ◽  
pp. 203-246
Author(s):  
Andrew Weber ◽  
Paul Rulis ◽  
Michelle Paquette ◽  
Konstantin Pohkhodyna ◽  
Saad Janjua ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Point Of View ◽  
Magnetic Exchange

scholarly journals Boron Concentration Induced Co-Ta-B Composite Formation Observed in the Transition from Metallic to Covalent Glasses

2020 ◽  
Vol 5 (1) ◽  
pp. 18
Author(s):  
Simon Evertz ◽  
Stephan Prünte ◽  
Lena Patterer ◽  
Amalraj Marshal ◽  
Damian M. Holzapfel ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Metallic Glasses ◽  
Boron Concentration ◽  
High Strength ◽  
Point Of View ◽  
Composite Formation ◽  
Structural Applications ◽  
Glassy Materials ◽  
Metallic Bonding ◽  
Composite Region

Due to their unique property combination of high strength and toughness, metallic glasses are promising materials for structural applications. As the behaviour of metallic glasses depends on the electronic structure which in turn is defined by chemical composition, we systematically investigate the influence of B concentration on glass transition, topology, magnetism, and bonding for B concentrations x = 2 to 92 at.% in the (Co6.8±3.9Ta)100−xBx system. From an electronic structure and coordination point of view, the B concentration range is divided into three regions: Below 39 ± 5 at.% B, the material is a metallic glass due to the dominance of metallic bonds. Above 69 ± 6 at.%, the presence of an icosahedra-like B network is observed. As the B concentration is increased above 39 ± 5 at.%, the B network evolves while the metallic coordination of the material decreases until the B concentration of 67 ± 5 at.% is reached. Hence, a composite is formed. It is evident that, based on the B concentration, the ratio of metallic bonding to icosahedral bonding in the composite can be controlled. It is proposed that, by tuning the coordination in the composite region, glassy materials with defined plasticity and processability can be designed.

Electronic structure and effective chemical and magnetic exchange interactions in bcc Fe-Cr alloys

2009 ◽  
Vol 79 (5) ◽  
Author(s):  
P. A. Korzhavyi ◽  
A. V. Ruban ◽  
J. Odqvist ◽  
J.-O. Nilsson ◽  
B. Johansson
Keyword(s):  
Electronic Structure ◽  
Exchange Interactions ◽  
Magnetic Exchange

scholarly journals Electronic structure, elasticity, Debye temperature and anisotropy of cubic WO 3 from first-principles calculation

2018 ◽  
Vol 5 (6) ◽  
pp. 171921 ◽  
Author(s):  
Xing Liu ◽  
Hui-Qing Fan
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Debye Temperature ◽  
Density Functional ◽  
Elastic Wave Velocity ◽  
Point Of View ◽  
First Principles Calculation ◽  
Shear Moduli ◽  
Charge Densities ◽  
Indirect Band Gap

The electron structure, elastic constant, Debye temperature and anisotropy of elastic wave velocity for cubic WO 3 are studied using CASTEP based on density functional theory. The optimized structure is consistent with previous work and the band gap is obtained by computing the electronic structure; the top of the valence band is not at the same point as the bottom of the conduction band, which is an indirect band-gap oxide. Electronic properties are studied from the calculation of band structure, densities of states and charge densities. The bulk and shear moduli, Young's modulus, hardness and Poisson's ratio for WO 3 are studied by the elastic constants. We calculated acoustic wave velocities in different directions and estimated the Debye temperature from the acoustic velocity. The anisotropy of WO 3 was analysed from the point of view of a pure wave and quasi wave.

Structural analysis of Gd6FeBi2 from single-crystal X-ray diffraction methods and electronic structure calculations

2019 ◽  
Vol 75 (5) ◽  
pp. 562-567 ◽  
Author(s):  
Jiliang Zhang ◽  
Yong-Mook Kang ◽  
Guangcun Shan ◽  
Svilen Bobev
Keyword(s):  
Electronic Structure ◽  
Single Crystal ◽  
First Principles ◽  
Earth Metal ◽  
Magnetic Ordering ◽  
Additional Contribution ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Magnetic Exchange ◽  
X Ray

The crystal structure of the gadolinium iron bismuthide Gd6FeBi2 has been characterized by single-crystal X-ray diffraction data and analyzed in detail using first-principles calculations. The structure is isotypic with the Zr6CoAl2 structure, which is a variant of the ZrNiAl structure and its binary prototype Fe2P (Pearson code hP9, Wyckoff sequence g f d a). As such, the structure is best viewed as an array of tricapped trigonal prisms of Gd atoms centered alternately by Fe and Bi. The magnetic-ordering temperature of this compound (ca 350 K) is much higher than that of other rare-earth metal-rich phases with the same or related structures. It is also higher than the ordering temperature of many other Gd-rich ternary phases, where the magnetic exchange is typically governed by Ruderman–Kittel–Kasuya–Yosida (RKKY) interactions. First-principles calculations reveal a larger than expected Gd magnetic moment, with the additional contribution arising from the Gd 5d electrons. The electronic structure analysis suggests strong Gd 5d–Fe 3d hybridization to be the cause of this effect, rather than weak interactions between Gd and Bi. These details are of importance for understanding the magnetic response and explaining the high ordering temperature in this material.

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