Fabrication and Characteristics of High- ${T}_{{c}}$ Superconducting/Magnetoresistive Mixed Sensors
2016
Bicrystal grain boundary La
0.7
Ca
0.3
MnO
3
(LCMO) tunneling magnetoresistance (TMR) mixed sensors with high-T
c
superconducting YBa
2
Cu
3
O
y
(YBCO) transformers have been designed and fabricated. The mixed sensors show an increase in low-field magnetoresistance (MR) ratios at low temperatures and an increase in the slope of low-field MR curve at temperatures below superconducting critical temperature T
c
, indicating that the flux related to the field indeed can be captured by the superconducting YBCO loop with a constriction associated to the LCMO TMR junctions. Furthermore, the spin polarization parameter P of 0.40 for LCMO at 10 K is obtained, and the temperature-dependent P can be fitted by the curves of P(T) ∝ (T
C
- T)
0.97±0.01
with T
C
= 296 K. The temperature dependence of surface magnetization M
S
(T) deduced from P(T) agrees with the theoretical models for M
S
(T) and leads to the conclusion that the charge carriers at the grain-interface boundary govern the tunneling conductivity for our bicrystal grain boundary junctions. In addition, the gain of mixed sensor as a function of temperature gets weaker as T approaching T
c
. According to the voltage noise level of 6.8 μV/Hz
1/2
and the low-field slope of resistance variation dR/dH ≈ 781 kΩ/T for the mixed sensor at 77 K, we obtain the field sensitivity S
H 1/2
of ~0.58 μT/Hz
1/2
.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
18
References
0
Citations
NaN
KQI