Critical Crossover Between Yosida--Kondo Dominant Regime and Magnetic Frustration Dominant Regime in the System of a Magnetic Trimer on a Metal Surface
Quantum Monte Carlo simulations were carried out for a system of a magnetic trimer on a metal surface. The magnetic trimer is arranged in two geometric configurations, viz. , isosceles and equilateral triangles. The calculated spectral density and magnetic susceptibility show the existence of two re...
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| Published in: | Journal of the Physical Society of Japan Vol. 81; no. 2; pp. 023706 - 023706-4 |
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| Main Authors: | , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
The Physical Society of Japan
15-02-2012
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| Online Access: | Get full text |
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| Summary: | Quantum Monte Carlo simulations were carried out for a system of a magnetic trimer on a metal surface. The magnetic trimer is arranged in two geometric configurations, viz. , isosceles and equilateral triangles. The calculated spectral density and magnetic susceptibility show the existence of two regimes: the Yosida--Kondo dominant regime and magnetic frustration dominant regime. Furthermore, a critical crossover between these two regimes can be induced by changing the configuration of magnetic trimers from an isosceles triangle to an equilateral triangle. |
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| Bibliography: | Magnetic trimer on metal surface. Separation between adatoms 1 and 2, $R_{12}=a$. $a$ is the surface lattice constant. Adatom 3 is moved along the direction of the arrow, maintaining the relation $R_{13}=R_{23}$. Spectral densities at adatom 3 in the system of Cr trimer on Au(111) at 54 K. The Fermi level is set as the energy reference. Parameters corresponding to Au(111) are set as follows: lattice constant $a=2.9$ $Å$, Fermi wave number $k_{\text{F}}=0.2$ $Å$ -1 , and half-bandwidth $D/2=0.5$ eV. For Cr adatoms, the energy level of $d$ electrons $\epsilon_{d}=-0.15$ eV, Coulomb repulsion $U=0.3$ eV, and $t_{12}=0.103$ eV. $\Delta=0.015$ eV results from the coupling between adatoms and the surface and results in the broadening of $d$ levels. As $k_{\text{F}}R_{12}=0.58$ and $k_{\text{F}}R_{13}<1.6$, the RKKY interaction between adatoms arising from $F_{ij}$ in eq. is ferromagnetic. In the system specified above, the magnitude of the AF interaction rising from $t_{ij}$ is much larger than that of the RKKY interaction, then the calculated densities are shown as a $t_{13}$ dependence. Contour plot of spectral densities at Fermi level at adatom 3 vs temperature and magnetic interaction. Contour spacing is 0.14. At each blue (white) point, the spectral density as a function of energy is shown in Fig. . Temperature dependence of magnetic susceptibilities at adatom 3 (solid lines) at magnitudes of interactions corresponding to arrows shown in Fig. . The dashed lines depict the universal shape of Kondo susceptibility with the effective Kondo temperatures $k_{\text{B}}T_{\text{K}}^{*}/\Delta=0.1$ and 0.2. The error at each calculated point is smaller than or equal to the radius of the solid circle in the figure. |
| ISSN: | 0031-9015 1347-4073 |
| DOI: | 10.1143/JPSJ.81.023706 |