Magnetoelastic anisotropy of antiferromagnetic materials

2019 ◽  
Vol 115 (24) ◽  
pp. 242403 ◽  
Author(s):  
Ping Sheng ◽  
Yali Xie ◽  
Yuhao Bai ◽  
Baomin Wang ◽  
Lei Zhang ◽  
...  
2020 ◽  
Vol 102 (22) ◽  
Author(s):  
Md. Rakibul Karim Akanda ◽  
In Jun Park ◽  
Roger K. Lake

Entropy ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 336 ◽  
Author(s):  
Bosiljka Tadić ◽  
Miroslav Andjelković ◽  
Milovan Šuvakov ◽  
Geoff J. Rodgers

Functional designs of nanostructured materials seek to exploit the potential of complex morphologies and disorder. In this context, the spin dynamics in disordered antiferromagnetic materials present a significant challenge due to induced geometric frustration. Here we analyse the processes of magnetisation reversal driven by an external field in generalised spin networks with higher-order connectivity and antiferromagnetic defects. Using the model in (Tadić et al. Arxiv:1912.02433), we grow nanonetworks with geometrically constrained self-assemblies of simplexes (cliques) of a given size n, and with probability p each simplex possesses a defect edge affecting its binding, leading to a tree-like pattern of defects. The Ising spins are attached to vertices and have ferromagnetic interactions, while antiferromagnetic couplings apply between pairs of spins along each defect edge. Thus, a defect edge induces n − 2 frustrated triangles per n-clique participating in a larger-scale complex. We determine several topological, entropic, and graph-theoretic measures to characterise the structures of these assemblies. Further, we show how the sizes of simplexes building the aggregates with a given pattern of defects affects the magnetisation curves, the length of the domain walls and the shape of the hysteresis loop. The hysteresis shows a sequence of plateaus of fractional magnetisation and multiscale fluctuations in the passage between them. For fully antiferromagnetic interactions, the loop splits into two parts only in mono-disperse assemblies of cliques consisting of an odd number of vertices n. At the same time, remnant magnetisation occurs when n is even, and in poly-disperse assemblies of cliques in the range n ∈ [ 2 , 10 ] . These results shed light on spin dynamics in complex nanomagnetic assemblies in which geometric frustration arises in the interplay of higher-order connectivity and antiferromagnetic interactions.


2013 ◽  
Vol 646 ◽  
pp. 59-66 ◽  
Author(s):  
Arcady Zhukov ◽  
Margarita Churyukanova ◽  
Lorena Gonzalez-Legarreta ◽  
Ahmed Talaat ◽  
Valentina Zhukova ◽  
...  

We studied the effect ofthe magnetoelastic ansitropy on properties of nanostructured glass-coated microwires with soft magnetic behaviour (Finemet-type microwires of Fe70.8Cu1Nb3.1Si14.5B10.6, Fe71.8Cu1Nb3.1Si15B9.1 and Fe73.8Cu1Nb3.1Si13B9.1 compositions) and with granular structure (Cu based Co-Cu microwires). The magnetoelastic energy originated from the difference in thermal expansion coefficients of the glass and metallic alloy during the microwires fabrication, affected the hysteresis loops, coercivity and heat capacity of Finemet-type microwires. Hysteresis loops of all as-prepared microwires showed rectangular shape, typical for Fe-rich microwires. As expected, coercivity, HC, of as-prepared microwires increases with decreasing of the ratio ρ defined as the ratio between the metallic nucleus diameter, d to total microwire diameter, D. On the other hand we observed change of heat capacity in microwires with different ratio ρ. In the case of Co-Cu microwires ρ- ratio affected the structure and the giant magneto-resistance of obtained microwires.


2011 ◽  
Vol 84 (1) ◽  
Author(s):  
D. C. Leitao ◽  
J. Ventura ◽  
C. T. Sousa ◽  
A. M. Pereira ◽  
J. B. Sousa ◽  
...  

2003 ◽  
pp. 347-357
Author(s):  
Steen Mørup ◽  
Cathrine Frandsen ◽  
Franz Bødker ◽  
Stine Nyborg Klausen ◽  
Kim Lefmann ◽  
...  

2004 ◽  
Vol 59 (8) ◽  
pp. 869-876 ◽  
Author(s):  
L. Engelke ◽  
R. Stähler ◽  
M. Schur ◽  
C. Näther ◽  
W. Bensch ◽  
...  

AbstractThe two new compounds Mn2(L)Sb2S5 (L = diethylenetriamine = DIEN, N-methyl-1,3- diaminopropane = MDAP) were prepared under solvothermal conditions using the elements as starting materials. Both compounds crystallise in the monoclinic space group P21/c with the lattice parameters a=10.669(7), b=12.805(2), c=12.072(1)Å , β =115.786(7)°,V =1485.1(4) Å3 for L = DIEN and a = 10.1859(7), b = 12.7806(6), c = 12.1256(8)Å , β = 110.173(8)°, V = 1481.7(2) Å3 for L = MDAP and Z = 4. The primary building units are SbS3 pyramids, MnS6 and MnS4N2 distorted octahedra. These primary building blocks are interconnected to form Mn2Sb2S4 hetero-cubane units. The hetero-cubanes share common corners, edges and faces thus forming a second heterocubane. These secondary building units are joined to form layers within the (100) plane. The connection mode yields ellipsoidal pores within the layers. The amines are exclusively bound to one of the two crystallographically independent Mn2+ cations and they point into the pores and between the layers separating the layers from each other. The interlayer separation and the size of the pores depend on the sterical requirements of the amine incorporated into the network. A pronounced distortion of the MnS4N2 octahedron results from a significant elongation of one Mn-S distance from 2.866 Å (L = methylamine, MA) to 3.185 Å for L = MDAP. The magnetic susceptibility curves are typical for low-dimensional antiferromagnetic materials and the large negative values for the Weiss constant Θ indicate strong antiferromagnetic exchange interactions. The magnetic properties are significantly influenced by the change of the Mn-S bonds introduced by the different amines. The compounds decompose at elevated temperatures with a two step reaction for L = MA and ethylenediamine and in a one step reaction for the bidentate acting amine molecules.


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