Electric-field activated variable-range hopping transport inPrBa2Cu3

Ramp-type junction parameter control by Ga doping of PrBa2Cu3O7−δ barriers

“…This would be consistent with the absolute value for the barrier zero-bias resistivity (ϳ10 3 ⍀ cm), as it is already not far from reported values for PBCO thin films at 4.2 K, ab Ϸ10 3 -10 4 ⍀ cm. 21,22 Figure 5 shows the exponential decay of the critical current density versus PBCGO barrier thickness d, at 4.2 and 40 K. Note that up to 45 K the decay parameter (ϭ1.7 Ϯ0.3 nm) remains unchanged. This makes a proximityeffect type of coupling improbable at least up to 0.5T c .…”

Study of SrTiO3 thin films grown by sputtering technique for tunnel barriers in quasiparticle injection contacts

“…In high electric fields l VRH reaches toward a constant minimum value of about 4 nm in the direction of the applied field. This minimum has been interpreted in terms of nearest-neighbor hopping between LS [23]. Moreover, this value is in accordance with the average distance between two LS, namely ℓ 0 ≈1= ffiffiffi g 3 p ≈1= ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 10 20 =cm 3 3 q ≈3nm.…”

“…At low T and in weak fields the tunneling current is carried by a few hops over a long distance. At higher T or equivalently in higher electric fields the tunneling current is carried by more hops over a shorter distance [23]. In high electric fields l VRH reaches toward a constant minimum value of about 4 nm in the direction of the applied field.…”

Особенности транспортных свойств соединения Lu-=SUB=-0.1-=/SUB=-Bi-=SUB=-1.9-=/SUB=-Te-=SUB=-3-=/SUB=-

“…Это поведение согласуется с ме-ханизмом туннелирования носителей заряда в процессе прыжковой проводимости. Известно, что в области прыжковой проводимости зависимость ρ(E) отличается для слабых полей (при выполнении условия eε r Er ≪ kT , где ε r -относитель-ная диэлектрическая проницаемость материала и r -средняя длина прыжка носителя заряда) и сильных полей (когда eε r Er ≫ kT ) [9]. Важно, что в сильных электрических полях удельное сопротивление при воз-растании электрического поля уменьшается по закону p(E) ∼ exp(E −1/3 ).…”