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The Complexity of Ferromagnetic Two-spin Systems with External Fields [article]

Jingcheng Liu, Pinyan Lu, Chihao Zhang
2014 arXiv   pre-print
We study the approximability of computing the partition function for ferromagnetic two-state spin systems.  ...  In contrast to these two results, we prove that for any ferromagnetic two-state spin systems except the Ising model, there exists a threshold for external fields beyond which the problem is #BIS-hard,  ...  It is more interesting and intriguing (both physically and computationally) to understand the computational complexity of a uniform spin system (β, γ, µ) with the same external field µ on all the vertices  ... 
arXiv:1402.4346v1 fatcat:iqlhq5ejkjby7caic23lnljrry

The Complexity of Ferromagnetic Two-spin Systems with External Fields

Jingcheng Liu, Pinyan Lu, Chihao Zhang, Marc Herbstritt
2014 International Workshop on Approximation Algorithms for Combinatorial Optimization  
We study the approximability of computing the partition function for ferromagnetic two-state spin systems.  ...  In contrast to these two results, we prove that for any ferromagnetic two-state spin systems except the Ising model, there exists a threshold for external fields beyond which the problem is #BIS-hard,  ...  For general ferromagnetic spin systems with external field, the approximability is less clear.  ... 
doi:10.4230/lipics.approx-random.2014.843 dblp:conf/approx/LiuLZ14 fatcat:fwitvao7izfere56ytuag3qrli

Dynamic magnetization in non-Hermitian quantum spin systems

X. Z. Zhang, L. Jin, Z. Song
2020 Physical review B  
We report a global effect induced by the local complex field, associated with the spin-exchange interaction.  ...  The (N+1)-order coalescent level is a saturated ferromagnetic ground state in the isotropic spin system.  ...  Acknowledgments We acknowledge the support of the National Natural  ... 
doi:10.1103/physrevb.101.224301 fatcat:uivuiacc4fbe5a3fnccxypv3wm

Yang-Lee Edge Singularity Of The Infinite-Range Ising Model

Seung-Yeon Kim
2015 Zenodo  
In addition, we compare the Yang-Lee edge singularity of the infinite-range Ising ferromagnet with that of the square-lattice Ising ferromagnet in an external magnetic field.  ...  We study analytically the partition function zeros in the complex magnetic-field plane and the Yang-Lee edge singularity of the infinite-range Ising ferromagnet in an external magnetic field.  ...  This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant number NRF-2014R1A1A2056127).  ... 
doi:10.5281/zenodo.1099170 fatcat:4n6pytgrmvdrhk6mruoa3nge7y

Proximity effects in Graphene and Ferromagnetic CrBr3 van der Waals Heterostructure

Sushant Kumar Behera, Mayuri Bora, Sapta Sindhu Paul Chowdhury, P. Deb
2019 Physical Chemistry, Chemical Physics - PCCP  
We report on first-principle calculations on magnetic proximity effect in a van der Waals heterostructure formed by a graphene monolayer induced by its interaction with a two-dimensional (2D) ferromagnet  ...  We have considered density functional calculations with ferromagnetic ground state ordering of the system.  ...  With the variation of external electric field the modulation of band gap occurs and changes around 80 meV.  ... 
doi:10.1039/c9cp05252f fatcat:hnck5c7fcnatzdi2t7bdcn2gnu

Filtration of Spin Wave Signals at Transmission of Data Through a Ferromagnetic Medium

Yu.I. Gorobets, S.A. Reshetnyak, T.A. Khomenko
2008 Data Science Journal  
In this paper, we calculate the dependencies of spin wave reflection intensity on frequency and external magnetic field for a ferrogarnet structure in an exchange mode, for which the influence of the magnetostatic  ...  part of the energy is neglected as compared with the exchange part.  ...  with external magnetic field at  ... 
doi:10.2481/dsj.7.167 fatcat:hjpinegtjrd3bltx524vw4vzhi

Random-fieldp-spin-glass model on regular random graphs

Yoshiki Matsuda, Hidetoshi Nishimori, Lenka Zdeborová, Florent Krzakala
2011 Journal of Physics A: Mathematical and Theoretical  
One of our most interesting findings is that a thermodynamic spin glass phase is present in the three-body purely ferromagnetic model in random fields, unlike for the canonical two-body interaction random-field  ...  We investigate in detail the phase diagrams of the p-body +/-J Ising model with and without random fields on random graphs with fixed connectivity.  ...  YM is grateful for the financial support provided through the Japan Society for the Promotion of Science (JSPS) Research Fellowship for Young Scientists Program.  ... 
doi:10.1088/1751-8113/44/18/185002 fatcat:uzasxch4wjeolk5cfhiv6kh3qm

Organic magnetoelectric and optomagnetic couplings: perspectives for organic spin optoelectronics

Zhongxuan Wang, Wei Qin
2021 NPG Asia Materials  
Hopefully, the understanding of magnetoelectric and optomagnetic couplings could provide guidance for the further development of organic spin optoelectronics.  ...  AbstractOver the past years, the development of organic ferromagnetic materials has been investigated worldwide for potential applications.  ...  Conflict of interest The authors declare no competing interests.  ... 
doi:10.1038/s41427-021-00291-2 fatcat:iip5gvk2zfcqjdiil2iabfkgbu

Generating Two-dimensional Ferromagnetic Charge Density Waves via External Fields [article]

Heng Jin, Jiabin Chen, Yang Li, Bin Shao, Bing Huang
2022 arXiv   pre-print
Under external tensile strain, two novel ferromagnetic CDWs (√(3)×√(3) and 2×2√(3) CDWs) can be generated, accompanied by distinguishable lattice reconstructions of magnetic V atoms.  ...  Remarkably, because the driving forces for generating these two ferromagnetic CDWs are strongly spin-dependent, fundamentally different from that in conventional CDWs, the √(3)×√(3) and 2×2√(3) CDWs can  ...  The authors thank Prof. Z. Liu for helpful discussions. This work is supported by the NSFC (Grant No. 12088101) and NSAF (Grant No. U1930402).  ... 
arXiv:2204.11179v1 fatcat:eaqabb524bc6hcyymq2rdu5jdu

Imaginary Magnetic Fields in the Real World

Nerses Ananikian, Ralph Kenna
2015 Physics  
Imaginary or complex fields are, however, essential in the fundamental theory that underlies the statistical physics of phase transitions, such as those associated with the onset of magnetization.  ...  The response of the spins to changes in external parameters, such as the magnetic field or temperature, is given by functions such as the susceptibility. At the critical point, T c  ...  While this experiment focuses on complex zeros of the Lee-Yang type (i.e., in a complex external magnetic field) in a ferromagnetic system, one could imagine also looking for such Lee-Yang zeros in antiferromagnetic  ... 
doi:10.1103/physics.8.2 fatcat:y34hrcr5ezev7lk4sfuhip55uq

Anomalous magnetic behavior and complex magnetic structure of proximate LaCrO3 LaFeO3 system [article]

Brajesh Tiwari, Ambesh Dixit, M. S. Ramachandra Rao
2019 arXiv   pre-print
We investigated complex magnetic properties of multifunctional LaCrO3-LaFeO3 system.  ...  The onset of weak ferrimagnetic ordering is attributed to the competing complex interaction between two AFM LaCrO3-LaFeO3 sublattices.  ...  Considering the complex magnetic interactions in pristine systems, DC magnetization as function of temperature from 350 K to 100 K has been recorded under zero field cooled (ZFC) and field cooled (FC)  ... 
arXiv:1908.06450v1 fatcat:cw7s4re3n5g2laawcakxjsbfky

Field-induced ferromagnetism in one-dimensional tight-binding lattices

Giuseppe Della Valle, Stefano Longhi
2013 Europhysics letters  
Our analysis is validated by numerical simulations in a low-density system of 2-particles on a lattice with 11 sites.  ...  It is shown that a high-frequency electric field can be exploited to induce artificial ferromagnetism and eventually control anti-ferromagnetic/ferromagnetic phase transition.  ...  (c) Expectation value of the total spin operator S 2 tot for the first two eigenstates of the system.  ... 
doi:10.1209/0295-5075/101/67006 fatcat:odrubdzmfva3deeunmv34b3qbu

Is demagnetization an efficient optimization method?

S. Zapperi, F. Colaiori, L. Dante, V. Basso, G. Durin, A. Magni, M.J. Alava
2004 Journal of Magnetism and Magnetic Materials  
Demagnetization, commonly employed to study ferromagnets, has been proposed as the basis for an optimization tool, a method to find the ground state of a disordered system.  ...  Here we present a detailed comparison between the ground state and the demagnetized state in the random field Ising model, combing exact results in d=1 and numerical solutions in d=3.  ...  The spins are coupled to their nearestneighbors spins by a ferromagnetic interaction of strength J and to the external field H.  ... 
doi:10.1016/j.jmmm.2003.12.627 fatcat:gmlqxwtuzzevnjpznau7d6hziy

Successive spin glass, cluster ferromagnetic, and superparamagnetic transitions in RuSr2Y1.5Ce0.5Cu2O10 complex magneto-superconductor

A. Kumar, R. P. Tandon, V. P. S. Awana
2012 European Physical Journal B : Condensed Matter Physics  
Frequency and field dependent detailed AC magnetic susceptibility measurements confirms the spin-glass (SG) behavior with homogeneous/non-homogeneous ferromagnetic (FM) clusters in this system.  ...  Variation of cusp position with applied AC frequency follows the famous Vogel-Fulcher law, which is commonly accepted feature for spin-glass (SG) system with homogeneous/non-homogeneous ferromagnetic clusters  ...  Acknowledgements The authors from NPL would like to thank Prof. R. C. Budhani  ... 
doi:10.1140/epjb/e2012-30075-5 fatcat:sa47k2nukrcgvcesxifbka3ifm

Transverse spin waves in isotropic ferromagnets [article]

V. P. Mineev
2005 arXiv   pre-print
The transverse spin waves frequency in polarized paramagnetic Fermi liquid as well in a Fermi liquid with spontaneous magnetization is found to be proportional to the square of the wave vector with complex  ...  This behavior of polarized Fermi liquid contrasts with the behavior of Heisenberg ferromagnet in hydrodynamic regime where the transverse spin wave attenuation appears in terms proportional to the wave  ...  of magnetization M in ferromagnetic state and H 0 is an external magnetic field.  ... 
arXiv:cond-mat/0507676v1 fatcat:zqww5e6e2fad7oexyrtahoo2wu
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