scholarly journals Spin State Switching in Heptauthrene Nanostructure by Electric Field: Computational Study

2021 ◽  
Vol 22 (24) ◽  
pp. 13364
Author(s):  
Karol Szałowski

Recent experimental studies proved the presence of the triplet spin state in atomically precise heptauthrene nanostructure of nanographene type (composed of two interconnected triangles with zigzag edge). In the paper, we report the computational study predicting the possibility of controlling this spin state with an external in-plane electric field by causing the spin switching. We construct and discuss the ground state magnetic phase diagram involving S=1 (triplet) state, S=0 antiferromagnetic state and non-magnetic state and predict the switching possibility with the critical electric field of the order of 0.1 V/Å. We discuss the spin distribution across the nanostructure, finding its concentration along the longest zigzag edge. To model our system of interest, we use the mean-field Hubbard Hamiltonian, taking into account the in-plane external electric field as well as the in-plane magnetic field (in a form of the exchange field from the substrate). We also assess the effect of uniaxial strain on the magnetic phase diagram.

2012 ◽  
Vol 391 ◽  
pp. 012029 ◽  
Author(s):  
Yukihiro Kawamura ◽  
Sakiyo Tanimoto ◽  
Takashi Nishioka ◽  
Hiroshi Tanida ◽  
Masafumi Sera ◽  
...  

MRS Bulletin ◽  
1990 ◽  
Vol 15 (6) ◽  
pp. 50-54 ◽  
Author(s):  
A.P. Malozemoff

Among the many surprises in the held of high temperature superconductivity, new features discovered in the magnetic phase diagram are among the most exciting and controversial, generating many new physical concepts and impacting practical applications. This brief review complements several other recent reviews and refers mostly to the bulk crystal (not ceramic) Y1Ba2Cu3O7 and Bi2Sr2Ca1Cu2Ox materials, from now on denoted YBaCuO and BiSrCaCuO.The magnetic phase diagram of a conventional type II superconductor as a function of magnetic held H and temperature T is well known and understood in the mean-field Ginzburg-Landau and London theories. As shown in Figure 1a, a Meissner phase characterized by complete flux exclusion appears at low fields, delineated by a mean-field phase transition line called the lower critical field Hc1(T), which increases linearly with decreasing temperature below Tc and then saturates at low temperature. A second mean-field phase transition line, called the upper critical field Hc2(T), delineates the transition between the normal and superconducting states and shows a T-dependence similar to Hc1(T). In a strongly type II superconductor (in which the penetration depth λ is much larger than the coherence length ξ), the large region intervening between Hc1 and Hc2 is called the Abrikosov mixed phase. Here magnetic field penetrates the superconductor in the form of tubes of magnetic field called flux lines or vortices. In an ideal isotropic superconductor, these vortices self-organize into a hexagonal array. Defects disturb the hexagonal long-range order, causing the array to break up into a kind of glassy state with more or less short-range order.


2011 ◽  
Vol 84 (10) ◽  
Author(s):  
V. Fritsch ◽  
P. Pfundstein ◽  
P. Schweiss ◽  
E. Kampert ◽  
B. Pilawa ◽  
...  

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