Role of the Andreev current in bolometers and calorimeters

based on tunnel junctions T. Faivre , D. Golubev, K. Viisanen and J.P. PekolaLow Temperature Detectors Workshop, July 20th

2

Hybrid tunnel junctions

Mot

ivat

ion

3

Outline

• NIS thermometer• RF-NIS micro-calorimeter• Quasiparticle thermometer• Limitation due to γ parameter

• Andreev current • Andreev reflection• Subgap leakage• Zero-bias anomaly• Andreev thermometer

• Conclusion

Out

line

4

RF-NIS micro-calorimeter

Fast electron thermometry towards ultra-sensitive calorimetric detection S.Gasparinetti et al., Phys. Rev. Appl. 3, 014007.

NIS

t her

mom

eter

VH

5

RF-NIS micro-calorimeter

NIS

t her

mom

eter

Incomplete measurement of work in a dissipative two level system K. Viisanen et al., New J. Phys. 17, 055014 (2015).

6

Quasi-particles thermometer

NIS

t her

mom

eter

100

mK

7 mK

Tunnel junction thermometry down to millikelvin temperatures A. Feshchenko et al., ArXiv 1504.03841 .

7

Limitations due to γ parameter

NIS

t her

mom

eter

8

Outline

• NIS thermometer• RF-NIS micro-calorimeter• Quasiparticle thermometer• Limitation due to Andreev tunneling

• Andreev current • Andreev reflection• Subgap leakage• Zero-bias anomaly• Andreev thermometer

• Conclusion

Out

line

9

Andreev reflection

Subgap conductivity of a superconductor —normal-metal tunnel interface F.W.J. Hekking et al. , Phys.Rev.B, 49,6857 (1994).

And

reev

cu

rre

n t

10

Subgap leakage in SINIS devices

And

reev

cur

ren t

Experimentally,

Al (20 nm)

Ti (17 nm)

Al (3nm)AlOx

11

Zero-bias anomaly

Al (20 nm)

Au (10 nm)

Ti (20 nm)

Ti (2nm)Al (3nm)AlOx

Andreev Current for low temperature thermometry T. Faivre et al. , Appl. Phys. Lett. 106, 182602, (2015).

And

reev

cur

ren t

12

Zero-bias thermometer

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

2

4

6

8

10

12

x 105

Tbath

(K)

R0(

)

data

AndreevR

qp

Temperature saturation

qp saturation : I

Andreev current Ia,n

SINIS resistance

a,s fits

And

reev

cur

ren t

13

Perfomance

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

2

4

6

8

10

12

x 105

Tbath

(K)

R0(

)

data

AndreevR

qp

Temperature saturation

qp saturation : I

Andreev current Ia,n

SINIS resistance

a,s fits

And

reev

cur

ren t

14

Role of the Andreev current in bolometers and calorimeters based on tunnel junctions

Con

c lus

ion

Zero-bias thermometer :No shot noiseBetter heat insulation

But limited by Andreev tunneling

Andreev thermometer :Extend the temperature range toward mKConstant responsivity

15

Role of the Andreev current in bolometers and calorimeters based on tunnel junctions

Ref

er e

nce s

Incomplete measurement of work in a dissipative two level systemK.Viisanen et al., New J. Phys. 17, 055014 (2015).

Andreev Current for low temperature thermometry T. Faivre et al. , Appl. Phys. Lett. 106, 182602, (2015).

Tunnel junction thermometry down to millikelvin temperatures A. Feshchenko et al., ArXiv 1504.03841 (2015).

Fast electron thermometry towards ultra-sensitive calorimetric detection S.Gasparinetti et al., Phys. Rev. Appl. 3, 014007 (2015).

NIS thermometry

RF-NIS calorimetry

T. Faivre , D. Golubev, K.Viisanen and J.P. Pekola