Hall Effect under Pressure and Phase Transitions in the Organic Superconductors, κ-(BEDT-TTF)_2Cu(NCS)_2 and β-(BEDT-TTF)_2I_3
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The Hall effect, R<SUB>H</SUB> (T) of organic conductors, even if they are metallic, is strongly temperature dependent and varies with pressure. By increasing pressure, R<SUB>H</SUB> (T) converges to a single curve, which is typical to the structure of each Fermi surface, low temperature novel states or excitations are suppressed. When R<SUB>H</SUB> (T) deviates abruptly from the "typical" R<SUB>H</SUB> (T) -behavior, it is a strong signal for finding phase transitions or precursor. We show the example in κ- (BEDT-TTF) <SUB>2</SUB>Cu (NCS) <SUB>2</SUB> and in β- (BEDT-TTF) <SUB>2</SUB>I<SUB>3</SUB> with which anomaly in R<SUB>H</SUB> (T) corresponds to a peak (∼60 K) of antiferromagnetic fluctuation, and to 20 K- phase transition which is associated with tow-T<SUB>c</SUB> superconductivity, respectively. Further, it turned out that the simple temperature-independent R<SUB>H</SUB> (T) is only realized in a material where the Fermi surface is round and simple in these low dimensional systems.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 407-411, 1998
The Japan Society of High Pressure Science and Technology