De Haas-van Alphen

Shoenberg, D. (1960) The de Haas-van Alphen effect in copper, silver and gold, Phil. Mag., 5, 105-110. 

Mueller, F.M. and Priestley, M.G. (1966) Inversion of cubic de Haas-van Alphen data, with an application to palladium, Phys. Rev., 148, 638-643. 

High conductivity for transition metal complexes of TTF-dithiolate ligands have long been known, due to the mixing of n-d orbitals resulting in a small HOMO-LUMO gap [80]. At present, 17 is the most reliable metal in this category (ctrt = 4 X 10 S cmT, metallic down to 0.6 K) based on its purity, temperature dependencies of resistivity and magnetic susceptibility, and de Haas-van Alphen (dHvA) oscillations [48, 75]. 

Detailed studies - band structure calculations, de Haas-van Alphen effect and polarized neutron diffraction - have evidenced the strong hybridization of 5 f bands either with p anions bands (USi3, UGes, USns) or 4d bands (URhs, UIts). 

Table 6.2 de Haas-van Alphen frequencies used to calculate the Fermi surfaces. Values in parentheses are estimated frequencies... 

The Fermi surface of WC was proposed based on magnetoresistance and de Haas-van Alphen data taken under high magnetic fields at low temperatures. WC is a semimetal with equal numbers of electron and hole carriers of 1.5 X 1021/cm3. The Fermi surfaces consist of two electron pockets located at the point A and four hole pockets located at the point L, and at the point K or along the T A axis. These results indicate that the spin-orbit interaction is very important in WC. 

The transition metal carbides (TMC) are interesting because of their prominent properties such as great hardness, high electrical and thermal conductivities, stable field-electron emission1 and efficient catalysis.2 These properties are closely related to their electronic structures, yet the Fermi surfaces of TMC are not yet well established experimentally. In the case of hexagonal tungsten carbide (WC), there is only one reported experiment on the observation of de Haas-van Alphen oscillations.3... 

Table 6.1 Comparison of de Haas-van Alphen frequencies (F) of the floating zone-grown (FZ) WC crystal with those of the flux-grown (FL) crystal. The frequencies are in units of 102 tesla...

The Shubnikov-de Haas oscillations were observed by ac (337Hz) method with current (I=100pA) directed parallel to the c -axis. The de Haas-van Alphen oscillations were studied with cantilever torquemeter [4], The magnetic fields used were up to 14 T for both types of experiment and the temperature range was 1.5-4.2K. 

Shubnikov - de Haas (SdH) and de Haas - van Alphen (dHvA) quantum oscillations were observed in the crystals studied at different magnetic field directions and temperatures. Fig. 6 (inset) shows an example of these SdH oscillations. It should be noted that no beating node occurs in these oscillations, suggesting again a strong 2D... 

Figure 8. FFT spectrum for de Haas-van Alphen oscillations (inset) at T=1.5K and 0=14°. Only two frequensies F-i and F4 are visible.

So it cannot contribute to the magnetic oscillations giving rise to the de Haas-van Alphen effect. Fig. 8 (inset) shows the dHvA oscillations for the present salt at 1.5 K and the FFT is shown in Fig. 8. Only two frequencies, a and P, can be seen so that this can be taken as an additional confirmation of the fact that the (P-a) and (P-2a) frequencies are really connected with a QI effect. 

Falicov L.M. and Stachowiak H. (1966) The Theory of de Haas-van Alphen Effect in a system of Coupled Orbits. Application to Magnesium, Phys. Rev. 147,505-515. 

FIGURE 23 de Haas-van Alphen effect in superconducting YNi2B2C. The field-dependent torque signal is observed at 0.45 K. The magnetic field is rotated 45° from [001] to [100], arrows indicate the field-sweep directions. In the inset, after background subtraction, dHvA oscillations can be seen more clearly (Ignatchik et al., 2005). 

The dispersion of up in YNi2B2C has been confirmed by de Haas-van Alphen experiments (Goll et al., 1996). The values of Hc2(0) and Tc are reduced by the presence of the fast electrons that have only a moderate el-ph coupling. On the other hand, the positive curvature of H T) is caused by interband coupling between the slow and the fast electrons. In the example of Figure 25 the experimental... 

Keywords Antiferromagnet, phase transition, magnetic properties, de Haas-van Alphen effect... 

J.H. Condon, Nonlinear de Haas-van Alphen effect and Magnetic Domains in Beryllium, Phys.Rev. 145, 526-535 (1966)... 

Wang, G., P. K. Ummat, and W. R. Datars. 1988. De Haas-van Alphen effect of potassium intercalated graphite. Extended Abstracts, Graphite Intercalation Compounds, 217-219, Materials Research Society, Fall Meeting, Pittsburg, PA. 

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