Reduction factors for the icosahedralT1u⊗hgJahn-Teller system

Thermodynamic observation of a vortex melting transition in the Fe-based superconductor Ba0.5K0.5FeMak1, Philipp2, Cevey3 et al. 2013Phys. Rev. B167170View full textAdd to dashboardCite

“…Signatures of a vortex melting have been furthermore observed in some classical superconductors, but only in close proximity to the superconducting transition [22][23][24][25]. The vortex melting transition represents the only sharp phase transition in a magnetic field which can be either of a first-order or second order nature , depending on whether the solid phase is crystalline or glassy [10][11][12][13][14][15][16][17][18][19][20][26][27][28][29][30][31][32]. It is of particular importance for technical applications of superconductors, as only the solid vortex phase can show true zero resistance.…”

Accurate calculations of second-order vibronic reduction factors for C60ions

“…Electronic perturbations generate first-and second-order Hamiltonians describing the coupling within the orbital state of symmetry , as discussed in detail in [6] and [9], for example. The definition of the soRFs K (2) M ( l ⊗ m ) involving two perturbations, H (1) ( l ) of symmetry l and H (1) ( m ) of symmetry m , can be found in the general theory summarized in [10]. Their evaluation within the FC approximation for the icosahedral T 1 ⊗ h JT system has been described in detail in [5] and is summarized below.…”

“…The resultant ground states will be written as |0 σ i , where the '0' indicates that the oscillators in the wells are in their ground states. Following the notation developed in [10], we will write the vibronic ground states in a well p as |ψ p ; 0 , where the '0' again indicates that the localized oscillators in the wells are in their ground states. ψ p represents the vibronic state in a well expressed in a global reference frame common to all wells.…”

“…of the order of V −4 j ). We also note that, even though all wells are equivalent to each other, we have nevertheless retained the labels of the individual wells in equation (10) for reasons of clarity in the following calculations.…”

Anisotropic effect on the vibronic reduction factors

“…These factors can describe the energy splitting caused by magnetic field, strain and hyperfine effects because the reduction factor can not only reflect the influence of JT effect of the crystal on the spectrum, but also sufficiently describe the JT effect on some weak-perturbed systems. Therefore, many authors carried on the research of the reduction factors [2][3][4][5] of JT systems, including the icosahedral systems related to C 60 molecules. The experiments proved that the vibronic coupling have a quenching effect on the spin-orbit couplings, random strains and internal stresses, etc., and these effects can be explained by reduction factors.…”