Download Cryogenics Day cryogenic ltd 220910

Progress in Cryogenics
Jeremy Good
Cryogenic Ltd
16 Tesla Cryogen Free Magnet
Neutron Scattering and Beam-line
systems
5-Tesla HiFi Muon
Spectrometer Magnet
5 Tesla Cryogen Free Mini-Magnet
7 Tesla Fast Switching Mini
Cryogen Free Magnet
17 Tesla Cryogen Free Magnet for
Small Angle X-ray Scattering
Cryogen Free Dilution
Refrigerator down to 10mK
7 Tesla Cryogen Free
SQUID Magnetometer
12 Tesla System with top loading, Variable
Temperature Cryostat and Rotating Stand
Cryogen Free Variable
Temperature Cryostat
14 Tesla Vibrating Sample
Magnetometer
5 Tesla Mini-VSM
VSM data examples
Measurement 3: m(H) using low-field option.
A thin ferromagnetic film with a narrow hysteresis loop was measured with the magnet in low-field
regime. The time constant was 10 seconds and the Cryogenic VSM preamplifier was used.
The loop is shifted horizontally due to the effect of the remanent field in the magnet. In this case the
remanent field was +1.5 mT. The noise level as determined by standard deviation of the data between
20 and 30 mT is 9.7 10-7 emu.
moment, emu
5x10-4
0
-5x10-4
-30
-20
-10
0
10
20
Magnetic field, mT
30
40
VSM data examples
Measurement 1: magnetic moment as a function of field at fixed temperatures.
Measurement 2: magnetic moment as a function of continuously ramping temperature at fixed fields
Palladium cylinder. Sample courtesy of Prof. M Valente, University of Aveiro
µ0B = 2 T
µ0B = 1 T
µ0B = 0.01 T
0.04
0.2
0.0
T=
5K
10 K
50 K
100 K
150 K
200 K
250 K
270 K
-0.1
-0.2
-10
-5
0
magnetic field, T
5
10
magnetic moment, emu
magnetic moment, emu
0.03
0.1
0.02
0.01
1x10-3
0
50
100
150
200
250
300
0
50
100
150
200
250
300
5x10-4
0
Temperature, K
AC susc. data examples
Real part of AC susceptibility across an
antiferromagnetic phase transition. The peak
width of appox. 0.1 K is clearly resolved.
AC susceptibility with sample extraction from the coils set
and compensation of background signal.
1/χ, [emu/G]-1
8000
Gd2(SO4)3 8H2O
AC susceptibility measured at
frequency = 210.4 Hz
AC field amplitude = 1 mT
6000
4000
2000
0
0
50
100
150
200
Temperature, K
250
300
350
AC susc. data examples
In a spin glass the AC susceptibility is strongly affected by spin dynamics hence
the position of the phase transition depends on the frequency of the excitation
field.
The data demonstrate a regular frequency dependence and correct
discrimination between χ’ and χ’’ (i.e. the phase of the measured signal is set
accurately so that the contributions due to χ’ and χ’’ are separated correctly and
are not mixed).
4.0x10-4
3x10-3
2x10-3
30 Hz
60 Hz
300 Hz
600 Hz
900 Hz
-3
1x10
0
60
70
80
90
100
Temperature, K
110
120
χ'', emu/G
χ', emu/Oe
3.0x10-4
2.0x10-4
30 Hz
60 Hz
300 Hz
600 Hz
900 Hz
-4
1.0x10
0.0
60
70
80
90
100
Temperature, K
110
120
Resistance and Hall effect
Measurements of very low DC voltage is only possible by using reversing polarity. Otherwise
the signal is dominated by thermal voltages rendering the measurement inaccurate.
0.20
0.15
Voltage, microVolt
0.10
Standard resistor
T=2K
I-V curve using reverse polarity
R = 1.33 microOhms
0.05
0.00
-0.05
-0.10
-0.15
-0.20
-0.15
-0.10
-0.05
0.00
Current, Amp
0.05
0.10
0.15
Very low field option
The following four graphs show successive reduction of the field steps from 10 mT to 0.01 mT using the
low-current source. VSM measurements taken at 300 ms time constant without the preamplifier, hence the
noise level is 10-5 emu. Sample: NIST calibration sample (YIG sphere) at 298 K.
Resolution of the low-field source is 1
microTesla
50 mT
The full range is typically
m, emu
0.05
0.00
-0.05
-100
-50
0
B, mT
50
100
0.003
0.002
m, emu
0.001
0.000
-0.001
-0.002
-0.003
-3
-2
-1
0
B, mT
1
2
3
Heat capacity data example
Magneto-caloric material
Metallic sample
Sample courtesy of Dr S.Ozcan, University of Cambridge and Cambridge Ltd.
Heat capacity
AC calorimetry
method
 Sensor patterned
on a silicon nitride
membrane
 Ideal for small
samples
 Record sensitivity
1 nJ/K

Rotating Sample Probe
Mini Magnet for NMR
Baby-scan MRI magnet
Delivered Cryogen Free Magnet
Systems.