Evidence for Magnetism in the Low-Temperature Charge-Density-Wave Phase of NbSe3

Large enhancement of the resistive anomaly in the pentatelluride materialsHfTe5andZrTe5Tritt1, Lowhorn2, Littleton3 et al. 1999Phys. Rev. B7311560View full textAdd to dashboardCite

“…The low-dimensional pentatelluride materials, HfTe 5 and ZrTe 5 , first synthesized in 1973, 1 exhibit a peak in their resistivity as a function of temperature, T P Ϸ80 K for HfTe 5 and T P Ϸ145 K for ZrTe 5 , apparently the result of a phase transition. 2,3 In addition, both parent materials exhibit a large positive ͑p-type͒ thermopower (␣Ϸ150 V/K͒ near room temperature which undergoes a change to negative thermopower ͑n-type, ␣ϷϪ150 V/K) below the peak temperature with the zero crossing of thermopower T 0 , corresponding well with T P .…”

“…4 Early theories suggested that this resistive anomaly was probably due to a charge-density wave ͑CDW͒ transition, similar to that which occurs in NbSe 3 . 5 However, the absence of distinct superlattice spots in the x-ray diffraction patterns and the absence of nonlinear conductance, both indicative of CDW materials, seemed to quickly contradict this explanation. 6 Other experiments were attempted in an effort to ascertain the nature and origin of this yet undetermined transition.…”

Charge-Density-Wave Carrier Concentration in NbSe3as a Function of Magnetic Field and Temperature

“…When the CDW begins to slide a narrow-band noise (NBN) may be observed whose frequency F is linearly dependent on the current that is carried by the charge-density wave /CDW-The slope of the /CDW vs F curve is proportional to the CDW carrier concentration /?CDW. 3 Coleman et al 4 found that when a magnetic field was applied perpendicular to the high conductivity axis in NbSe3, a very large magnetoresistance Ap/p was observed at temperatures in the range 10 K < T < 50 K. They found that at B =22.7 T, Ap/p was on the order of 2-4 in the temperature range 20-45 K and that Ap/p went to zero at the lower CDW transition temperature. They emphasized that the resistive anomaly is not caused by any dynamical motion of the CDW but by the effect of the magnetic field on either the number or the mobility of the normal electrons.…”

“…7 We have observed a large magnetoresistance below the lower transition in agreement with others. 4,7,8 Nevertheless, over these parameter ranges the magnetic field has very little effect on the CDW carrier concentration as determined by the NBN measurements. The latter has implications for the magnitude of the effect calculated by Balseiro and Falicov 5,6 since it implies that the large increase in resistance is not primarily due to a decrease (increase) in normal carriers (CDW carriers).…”

Interlayer Tunneling In Stacked Junctions Of High Temperature Superconductors, Cdw Materials And Graphite

“…The interest to these studies was related with enormously high magnetoresistance at low temperatures [33]. To explain that it was predicted [34] that magnetic field can abolish Fermi surface pockets responsible for ungapped carriers and in this way contribute to the excess magneto-resistance.…”