• Title/Summary/Keyword: transition-metal magnetism

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Magnetic Properties of Transition Metal Monolayers on Ta(001) Surfaces

  • Youn, S.J.;Hong, S.C.
    • Journal of Magnetics
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    • v.13 no.4
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    • pp.140-143
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    • 2008
  • The magnetic and structural properties of transition metal (Mn, Fe, Co) monolayers on Ta(001) surfaces are investigated theoretically by using the first principles full-potential linearized augmented plane wave method. Mn and Fe monolayers become ferromagnetic on Ta(001) surfaces while Co monolayers becomes non-magnetic. The paramagnetism of Co monolayers is explained by the Stoner theory of magnetism. The magnetic coupling of a transition metal overlayer with a substrate is ascribed to the orbital hybridization between the s and d orbitals of the transition metal.

ELECTRONIC STRUCTURE AND MAGNETISM OF V/W(001) (V/W(001) 계의 전자 구조와 자성)

  • 장영록;김인기;이재일
    • Proceedings of the Korean Magnestics Society Conference
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    • 2002.12a
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    • pp.36-37
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    • 2002
  • 귀금속(noble metal)이나 전이금속(transition metal) 밑층(substrate) 위에 높여진 금속 웃층(metal overlayer)의 자성(magnetism) 연구는 오랫동안 많은 관심의 대상이 되었고, 특히 전이금속을 웃층으로 사용한 경우에 대해서 많은 연구가 있었다 [1]. 전이금속 중에서 바나듐(vanadium; V)은 덩치(bulk) 상태에서는 자성을 가지지 않지만, 귀금속인 Ag(001) 혹은Cu(001) 위에 놓여지면 자성을 가지게 된다는 보고가 있었다 [2]. (중략)

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STUDY OF MAGNETISM IN THE LAYERED TRANSITION METAL COMPOUND ${(C_{n}H_{2n+1}NH_{3})}_{2}CuCl_{4}\;(n=10,\;14)$

  • Lee, C.H.;Lee, K.W.;Lee, Cheol-Eui;Kang, J.K.
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.358-361
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    • 1995
  • We have investigated the quasi-two-dimensional magnetism for the layered transition metal compound (C/sub n/H/sub 2n+1/NH/sub 3/)/sub 2/CuCl/sub 4/ (n=10, 14) in the high temperature regions by means of EPR (Electron Paramagnetic Resonance) and SQUID measurements. As a result, the magnetic transitions were reflected in the EPR linewidths and the magnetic suceptibilities in a sensitive manner. Fluctuations of the magnetic susceptibility and a similar variation of the .DELTA. g =(g/sub .parallel. -/g/sub .perp. /)g/sub .parallel. / value were also observed around the structural phase transition temperatures.

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ROOM TEMPERATURE FERROMAGNETISM IN TRANSITION METAL DOPED OXIDE SEMICONDUCTORS, $TiO_2$ and ZnO

  • Y. H. Jeong;S-J. Han;Park, J.H.
    • Proceedings of the Korean Magnestics Society Conference
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    • 2003.06a
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    • pp.17-17
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    • 2003
  • Semiconductors with ferromagnetism at room temperature has been actively searched for in recent years; a prospect of devices using both charge and spin continuously gives impetus to the activities. Transition metal doped oxide materials have been of particular interest. Co substituted ZnO [1] and TiO$_2$ [2] thin films, for example, were reported to show ferromagnetic properties at room temperature. However, various studies do not seem to converge on a definite picture [3,4,5]. The issue is rather fundamental: whether a system shows ferromagnetic properties at all, and in case it does, whether the system possesses a close coupling between magnetism and transport properties. In this talk, we shall assess the current status of transition metal doped oxide materials as room temperature ferromagnetic semiconductors.

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Electronic Structure and Magnetism of (3d, 4d)-Pd Alloyed c(2×2) Monolayers (3d 및 4d 전이금속과 Pd가 c(2×2) 합금을 이룬 단층의 자성에 대한 제일원리 연구)

  • Kim, Dong-Chul;Choi, Chang-Sik
    • Journal of the Korean Magnetics Society
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    • v.20 no.3
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    • pp.83-88
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    • 2010
  • We investigated the electronic structure and magnetism of the (3d, 4d)-Pd alloyed c($2{\times}2$) monolayer systems, by use of the FLAPW band method. For comparison, pure 3d- and 4d-transition metal monolayers are also considered. We found that the antiferromagnetic configuration of pure V monolayers is sustained in the V-Pd alloy system, while the Ti-Pd alloy system is changed to antiferromagnetic configuration from the ferromagnetic state in pure Ti monolayer. The 4d TM (Mo, Ru, Rh)-Pd monolayers are found to be stable in ferromagnetic configurations. The magnetic moments of Ru and Rh atoms in Ru-Pd and Rh-Pd systems are almost same with those of pure Ru and Rh monolayers, while the magnetic moment of Mo atom is increased to $2.98\;{\mu}_B$ in Mo-Pd alloyed system from the value of Mo monolayer, $0.02\;{\mu}_B$.

Metal-Insulator Transition Induced by Short Range Magnetic Ordering in Mono-layered Manganite

  • Chi, E.O.;Kim, W.S.;Hong, C.S.;Hur, N.H.;Choi, Y.N.
    • Bulletin of the Korean Chemical Society
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    • v.24 no.5
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    • pp.573-578
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    • 2003
  • The structural, magnetic, and transport properties of a mono-layered manganite $La_{0.7}Sr_{1.3}MnO_{4+{\delta}}$ were investigated using variable temperature neutron powder diffraction as well as magnetization and transport measurements. The compound adopts the tetragonal I4/mmm symmetry and exhibits no magnetic reflection in the temperature region of 10 K ≤ T ≤ 300 K. A weak ferromagnetic (FM) transition occurs about 130 K, which almost coincides with the onset of a metal-insulator (M-I) transition. Extra oxygen that occupies the interstitial site between the [(La,Sr)O] layers makes the spacing between the [MnO₂] layers shorten, which enhances the inter-layer coupling and eventually leads to the M-I transition. We also found negative magneto resistance (MR) below the M-I transition temperature, which can be understood on the basis of the percolative transport via FM metallic domains in the antiferromagnetic (AFM) insulating matrix.