OPTIONS FOR S700X SERIES SQUID MAGNETOMETER SYSTEM

S/10 Dynamic range extender
The standard measurement range (10⁶ total dynamic range) from 10^-11 to 10^-5 Am² can be extended to measure signals as large as 5 x 10^-3 Am². This option increases the range of measurable total moments and is available as a retrofit option.

S/20 Extended temperature range
To perform measurements at above room temperature, an oven insert is offered which increases the standard temperature range. In normal operation, the system has a continuous temperature range of 1.6 to 300K. With the oven insert this can complemented by a temperature range of 200K to 600K.

S/30 Transverse measurement facility with sample rotation
Simultaneous multiple axis measurements are possible by the addition of secondary (and optionally tertiary) pick-up coils in the main magnet assembly for observation of, for example, anisotropic effects. Included with the secondary axis facility is a continuous motor which permits rotation of the sample, controllable to 0.1 degree. Pairs of coils are available for both axes at right angles to the applied field. This facility allows simultaneous measurement in two axes without reduction in the response time of the system, as well as offering measurements of axes which are not perpendicular to the applied field.

S/35 Transverse Field saddle coil
A small transverse field (~1Gauss) may be applied using an additional saddle coil mounted in the main coil. This uses a separate power supply and may be put in persistent mode via a superconducting switch. The transverse field is offered for the two measurement axis systems thereby providing field in parallel with the secondary axis pick up coils.

S/40 Fluxgate field measurement system
The fluxgate measures and profiles fields up to 20 gauss with a resolution of 10-5 gauss. For some applications it is very important to verify the magnet field at very low applied fields. The fluxgate allows measurement of magnet fields from 10-5 to 20 gauss with a resolution of 10-5 gauss. Additionally, the fluxgate can also profile the magnet along its entire length. This facility is recommended with the ultra low field option.

S/50 Hall probe field measurement facility
To compliment the fluxgate, we offer the Hall probe to enable the magnet field to be measured at higher fields. The Hall probe allows fields from 0.1 gauss to 10⁵ gauss to be profiled and measured, complimenting the fluxgate. For high accuracy, the zero offset must be referenced.

S/60 AC mode measurement facility
An AC measurement option is available as a complement to the standard DC method to study the magnetic susceptibility of materials directly. We offer the facility to perform direct susceptibility measurements in AC magnetic fields from 10^-2 to 500Hz. The magnet is fitted with a separate superconducting coil for the AC field, providing from 0.01 Gauss up to 5 Gauss AC field, and is driven by the main system electronics.

S/70 Ultra low field option
Using an accurate mA current source controlled via the main computer, fields as low as 3 mGauss can be applied to the main coil (after reducing any remnant field e.g. by quenching). The currents are applied via the main power supply from a secondary high stability 16 bit mA current source to the main magnet and fields as low as 3mGauss can be applied to the main coil. Experience has shown that field cycles below +/-250 Gauss do not exhibit significant remnant field on the superconducting magnet.

S/90 Hydrostatic Pressure cell option
The high-pressure generating technology as a means of physical-properties evaluation has developed considerably recently. The piston cylinder method for high-pressure generating equipment is often used for physical-properties research.

Custom Measurement Experiment Options
Cryogenic Limited can provide custom measurement options for your experiment. Transverse magnetic field coils, optical and microwave illumination of the sample are some examples of the custom options that can be provided. Please contact us with your experiment request.

S/100 He3 Insert OPTION FOR SQUID Magnetometer

The Cryogenic range of Helium-3 inserts is designed as an alternative to the standard sample probe and can be used in the liquid helium or cryogen free systems. The Helium 3 insert extends the range of experimental temperatures accessible in the SQUID magnetometer variable temperature sample space beyond the standard 1.6K-300K range. Using only the cooling power of the VTI and two internal temperature-controlled sorption pumps, the sample platform of the Helium-3 Insert can be maintained at any temperature from below 300mK to above 300K.

The miniaturized Helium-3 insert fits inside the 8mm SQUID Magnetometer VTI.
The sample sits on a cold finger composed of high purity silver. The insert has a
working volume of liquid 3He of 1.5cc and is sufficient to maintain temperatures
down to 300mK for up to 12 hours.

Helium-3 Insert Specifications

He-3 capacity:
Total He-3 gas volume 1.5 STP litres
Working volume in normal use approximately 1.0 STP litres

Initial Cooldown time:
2 hours from room temperature sample change to
3He condensation temperature under standard
cryogen-free VTI operating conditions

Recondensation time:
25 minutes to condense 90% of 3He charge and cool pot to below 2K

Performance:
24 hours at 285mK with zero load
12 hours at 340mK with 25μW load
3 hours at 550mK with 185μW load

S/110 RESISTIVITY AND HALL EFFECT OPTION

The Resistivity system is configured for 4-terminal resistance measurements and Hall
voltage measurements in the range μΩ to MΩ resistance. Automation of the system under
the LabVIEW operating environment provides not only system parameter control but
also data acquisition and processing of raw data. ASCII data files are provided for ease
of subsequent manipulation. Provision is made for scanning up to 5 samples at a time
during a single sequence of measurements is offered as an option.

The resistance is measured by a separate DVM and current source. The applied voltage
can be dynamically reversed in order to subtract thermal potentials, and the measurement
averaged. For each measurement the current will be set at a low level and increased to
provide an adequate measurement voltage. The maximum current, power or voltage on the
sample can be preset to avoid sample heating and/or damage.

As each measurement is performed the magnetic field and temperature are varied
according to a pre-arranged sequence. Different sequences can be stored and drawn
down by command, which generally simplifies operating procedures making the system
easy to use without a detailed knowledge of the system software and hardware.

Resistivity and Hall Effect Specifications:
- Two Keithley Instruments are used to provide a current source and voltage measurement.
The current source type 2400 provides currents over the range 1 nA to 1 A.
- The voltage measurement DVM type 2182 provides measurements over the range 100nV to 10V.
- Between these two instruments, resistivity over the range 109 ohm to 10-7 ohm are covered.
- Accuracy 0.01% typical except at the extremes of the range settings.
- A scanning facility is provided.

Maximum sample size: 10mm diameter
Resistance measurement range (DC): 10^-7 to 10⁹ Ohms
Voltage sensitivity (DC:) 1V to 0.1μV
Accuracy of resistance measurement: < 0.1% 1-10⁶ ohm

Key features:
• Applied DC current can be reversed to eliminate thermal potentials.
• Maximum current, power or voltage on the sample can be pre-set to avoid
sample heating and or damage.
• For each measurement the current is normally set low and increased to
provide an adequate measurement voltage