ZHANG Zhidong | |
Title:Professor | Email: zdzhang@imr.ac.cn |
Tel. : +86-24-23971859 | FAX: +86-24-23891320 |
Division: Magnetism and Magnetic Materials Division, Shenyang National Laboratory for Materials Science | |
Address: Magnetism and Magnetic Materials Division, Institute of Metal Research Chinese Academy of Sciences (IMR CAS), 72 Wenhua Road, Shenyang, China, 110016 |
Experience： |
197909-198307: Department of Physics, Nanjing University, received B.S. degree. 198309-198603: Institute of Metal Research, Chinese Academy of Sciences, Master degree. 198311-198910: Institute of Metal Research, Chinese Academy of Sciences, Ph.D degree. 198708-198809: visiting Ph.D student, Van der Waals - Zeeman Institute, University of Amsterdam. 198910-199205: Assistant Professor, Institute of Metal Research, Chinese Academy of Sciences. 199205-199301: Associate Professor, Institute of Metal Research, Chinese Academy of Sciences. 199301- : Professor, Institute of Metal Research, Chinese Academy of Sciences. 199501- : Head of the Department (Division) of Magnetism and Magnetic Materials, Institute of Metal Research, Chinese Academy of Sciences. 1999611-199712: Visiting scholar in Department of Physics, University of California at Berkeley. |
Research Interest： |
1) Rare – earth - transition - metal compounds. 2) Magnetic thin films, multilayers, quantum wells, quantum dots. 3) Magnetic nanoparticles and nanocapsules 4) Permanent magnets 5) Giant magnetoresistance materials 6) Giant magnetostrictive materials. 7) Magnetocaloric materials. 8) 3D Ising model; Critical phenomena. |
Research Achievement： |
1）Conjectures and mathematical structure of the three-dimensional (3D) Ising model We report the conjectures on the three-dimensional (3D) Ising model on simple orthorhombic lattices, together with details of calculations for a putative exact solution. Two conjectures, an additional rotation in the fourth curled-up dimension and the weight factors on the eigenvectors, are proposed to serve as a boundary condition to deal with the topologic problem of the 3D Ising model. The partition function, the critical temperature, the specific heat, the spontaneous magnetization, the spin correlation functions, the true range of the correlation, and the susceptibility of the 3D simple orthorhombic Ising model are evaluated by employing these conjectures. The critical exponents derived explicitly for the simple orthorhombic Ising lattices are a = 0, b = 3/8, g = 5/4, d = 13/3, h = 1/8 and n = 2/3, showing the universality behavior and satisfying the scaling laws. The golden (or silver) ratio is the largest solution for the critical temperature of the 3D (or 2D) Ising systems, corresponding the most symmetric simple cubic (or square) lattice. Furthermore, an outlook on the mathematical structure of the three-dimensional (3D) Ising model is given, from point view of topologic, algebraic and geometric aspects. 2） Opposite effect of spin-orbit coupling on condensation and superfluidity We investigated effects of a Rashba-type spin-orbit coupling (SOC) on the condensed density and superfluid density tensor of a two-component Fermi gas in the BCS-BEC crossover at zero temperature. In anisotropic three dimensions (3D), we found that SOC has an opposite effect on condensation (enhanced) and superfluidity (suppressed in the SOC direction) and this effect becomes most pronounced for very weak interactions and the SOC strength being larger than a characteristic value. 3）Magnetic and electromagnetic properties of magnetic nanocapsules We focused on synthesis of the magnetic nanocapsules and investigation of their magnetic and electromagnetic properties. The arc-discharge plasma, the chemical vapor deposition, high-temperature reaction, etc have been used to prepare more than thirty types of new nanocapsules. Based on the systematic studies of core-shell structures and growth mechanisms of different types of nanocapsules, we developed several new techniques for producing the magnetic nanocapsules, investigated systematically the structures, magnetic and electromagnetic properties and the relations between them. Furthermore, we developed new magnetic nanocapsules for possible applications in microwave absorption. 4) Angular dependent magnetoresistance in Nd_{0.45}Sr_{0.55}MnO_{3} thin film The angular dependent magnetoresistance (AMR) of Nd_{0.45}Sr_{0.55}MnO_{3} thin film epitaxially grown on SrTiO_{3} (001) is examined at different temperatures and magnetic fields. Twofold and fourfold symmetric AMR and a transition between them are observed under two different measurement modes and are found to be dependent on temperature and/or strength of a magnetic field. In comparison with AMR occurring in other systems, we believe that the twofold/fourfold symmetric AMR observed here corresponds to different spin-canted states induced by the magnetic field at certain temperatures below the Néel temperature. 5） Effects of anisotropy and competition between interfacial and interlayer coupling in trilayers Strong effects of ferromagnetic (FM) materials on the exchange coupling are observed at different temperatures in FM_{1}(3 nm) Cr2O_{3}(6 nm) FM_{2}(10 nm) trilayers with FM º Co, Fe, or Ni_{80}Fe_{20}. Changes of the anisotropy of FM and spin-asymmetry of the reflection coefficients for spin-up and spin-down electrons of FM contacted the antiferromagnetic layer influence the strength of interfacial and interlayer coupling of the trilayers. Thus, the reduction of the interfacial coupling and the enhancement of the interlayer coupling with increasing temperature result in quite different magnetic behavior of different trilayers. 6）Magnetocaloric effects and electrocaloric effects in compounds We focus our attention on magnetocaloric effects and electrocaloric effects in several compounds. For instance, reversible room-temperature magnetocaloric effect was observed in the Mn_{5}PB_{2} compounds. The compound Ho_{2}In exhibits two successive magnetic phase transitions: a spin-reorientation transition at T_{SR}=32 K and a magnetic-ordering transition at T_{C}=85 K. A large magnetic-entropy change (−20.6 J /kg K at 11 K for a field change of 7 T) together with small hysteresis was achieved in the Ising antiferromagnet DySb. Magnetic-field-induced martensitic phase transition and the concomitant change of volume are investigated in Ni–Mn–In alloy. Furthermore, roles of order of phase transition and stresses on intrinsic electrocaloric effects in ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymers were studied. The origin of large overestimation of the magnetic entropy changes calculated directly by Maxwell relation was discussed. |
Service to the International Professional Societies： |
200601--Institute of Physics Publishing China Sci Advisory Committee, Member. 200001-200312 Advisory Board Member of the Journal of Physics: Condensed Matters. |
Honors： |
Publication： |
[1] “Fermi level shifting, charge transfer and induced magnetic coupling at La0.7Ca0.3MnO3/LaNiO3 interface”, X.K. Ning, Z.J. Wang and Z.D. Zhang, Scientific Report (2015) accepted. [2] “High Curie temperature and coercivity performance of Fe3-xCrxSe4 nanostructures”, S.J. Li, D. Li, W. Liu and Z.D. Zhang, Nanoscale (2015) accepted. [3] “Granularity Controlled Non-Saturating Linear Magneto-resistance in Topological Insulator Bi2Te3 Films”, Z.H. Wang, L. Yang, X.J. Li, X.T. Zhao, H.L. Wang, Z.D. Zhang and Xuan P. A. Gao, Nano Letter 14 (2014) 6510. [4] “Large, tunable low-field magnetoresistance in La_{0.7}Sr_{0.3}MnO_{3}:NiO nanocomposite films modulated by microstructures”, X.K. Ning, Z.J. Wang, Z.D. Zhang, Adv. Funct. Mater. 24 (2014) 5393. [5] “Experimental observation of Dirac-like surface states and topological phase transition in Pb1-xSnxTe (111) films”, C.H. Yan, J.W. Liu, Y.Y. Zang, J.F. Wang, Z.Y. Wang, P. Wang, Z.D. Zhang, L.L. Wang, X.C. Ma, S.H. Ji, K. He, L. Fu, W.H. Duan, Q.K. Xue, and X. Chen, Phys. Rev. Lett. 112 (2014) 186801. [6] “Fidelity susceptibility and topological phase transition of a two dimensional spin-orbit coupled Fermi superfluid”, X.B. Luo, K.Z. Zhou, W.M. Liu, Z.X. Liang, and Z.D. Zhang, Phys. Rev. A 89 (2014) 043612. [7] “Flower-like dynamics of coupled Skyrmions with dual resonant modes by a single-frequency microwave field”, Y.Y. Dai, H. Wang, T. Yang, W.J. Ren, Z. D. Zhang, Scientific Report 4 (2014) 6153. [8] “Unveiling the electronic origin of anion order in CrO_{2-x}F_{x}”, B. Li, Y.N. Chen, H. Wang, W. Liang, G.Y. Liu, W.J. Ren, C.F. Li, Z.Q. Liu, G.H. Rao, C.Q. Jin and Z.D. Zhang,. Chem. Commun. 50 (2014) 799. [9] “Microwave absorption properties of core double-shell FeCo/C/BaTiO_{3} nanocomposites”, J.J. Jiang, D. Li, D.Y. Geng, J. An, J. He, W. Liu and Z.D. Zhang, Nanoscale 6 (2014) 3967. [10] “Mathematical structure of the three - dimensional (3D) Ising model”, Z.D. Zhang, Chinese Phys. B 22 (2013) 030513. [11] “Ambipolar surface conduction in ternary topological insulator Bi_{2}(Te_{1-x}Se_{x})_{3} nanoribbons”, Z.H. Wang, Richard L. J. Qiu, C.H. Lee, Z.D. Zhang and Xuan P. A. Gao, ACS Nano 7 (2013) 2126. [12] “Broadband microwave absorption of CoNi@C nanocapsules enhanced by dual dielectric relaxation and multiple magnetic resonances”, H. Wang, Y. Y. Dai, W. J. Gong, D. Y. Geng, S. Ma, D. Li, W. Liu, Z. D. Zhang, Appl. Phys. Lett. 102 (2013) 223113. [13] “Skyrmion ground state and gyration of skyrmions in magnetic nanodisks without the Dzyaloshinskii-Moriya interaction”. Y. Y. Dai, H. Wang, P. Tao, T. Yang, W.J. Ren, Z. D. Zhang, Phys. Rev. B 88 (2013) 054403. [14] “Understanding strong magnetostriction in Fe_{100-x}Ga_{x} alloys”, H. Wang, Y. N. Zhang, R. Q. Wu, L. Z. Sun, D. S. Xu, and Z. D. Zhang, Scientific Report, 3 (2013) 03521. [15] “Opposite effect of spin-orbit coupling on condensation and superfluidity”, K.Z. Zhou and Z.D. Zhang, Phys. Rev. Lett. 108 (2012) 025301. [16] “High Curie temperature Bi_{1.85}Mn_{0.15}Te_{3} nanoplates”, L.N. Cheng, Z.G. Chen, S. Ma, Z.D. Zhang, Y. Wang, H.Y. Xu, L. Yang, G. Han, K. Jack, G.Q. Lu and J. Zou, J. American Chem. Soc. 134 (2012) 18920. [17] “Conjectures on the exact solution of three - dimensional (3D) simple orthorhombic Ising lattices”, Z. D. Zhang, Philosophical Magazine 87 (2007) 5309. |
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