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Spectromag

Oxford Instruments

Spectromag Magneto-optical system 1.5 K, 8 T

Split-pair superconducting magnet system provides optical access to a sample in a  variable horizontal magnetic field and low temperature environment. System features include:

• Magnetic fields up to 11 T in a compact geometry
• Inserts to provide sample temperatures from 0.45 K to 300 K with optical access
• Cryostat incorporating rectangular tail unit, providing excellent optical access to the sample
• Wide range of windows for measurements from near ultra-violet to far infra-red
• Option for fully automatic control

Custom magneto-optical system can be supplied to be able to perform both magnetic circular dichroism) and time-resolved magneto-optical kerr effect (TR-MOKE) measurements.
  • Specifications
  • System Components/Options
  • Windows
  • Applications
  • PDFs

Superconducting Magnet Horizontal field split pair magnet

Central field

8 T at 2.2 K
7 T at 4.2 K

10 T at 4.2 K

11 T at 2.2 K
10 T at 4.2 K

Time to full field

< 10 minutes

< 15 minutes

< 20 minutes

Homogeneity over a 10 mm
diameter sphere

0.6%

Stability in persistent mode

1 x 10-4 /hour

Liquid helium consumption with zero
flow through insert and zero current
in leads

185 cc/hour

Usable liquid helium volume

20 litres providing > 100 hr hold time

Liquid nitrogen consumption

0.5 litres/hour

Liquid nitrogen volume

24 litres providing 48 hr hold time

Optical access

OVC with 4 off horizontal optical access, two parallel to field, two perpendicular to field, fitted with Spectrosil B quartz windows
Radiation shield with 4 off horizontal optical access, two parallel to field, two perpendicular to field, fitted with re-entrant bore tubes

Overall system height

1.4 m approx.

1.45 m approx.

1.45m approx.

System weight  (without cryogens)

135 kg approx.

145 kg approx.

145 kg approx.


Integral variable temperature insert (VTI)

Sample space

25 mm

Temperature range
(measured at heat exchanger)

4.2 - 300 K (with GF4 pump) 1.5 - 300 K (with EPS40 pump)

Temperature stability

± 0.1 K (measured over a 10 minute period)

Optical access

4 off horizontal optical access, two parallel to field, two perpendicular to field, fitted with Spectrosil B quartz windows

Superconducting magnet

• 4 sets of optical windows in strain-free mounts
• Choice of 7 (8) T  or 10 (11) T at 4.2 (2.2) K
• Homogeneity 0.6% over a 10 mm diameter sphere
• Field sweep rate up to 1 T/min
• Stability in persistent mode < 0.01 %/hour
• Low LHe boil-off with > 100 hour static liquid helium hold time

The magnet tail is designed to reduce the volume of helium around the magnet, and maximise the optical access; there is no liquid helium in the optical path.

Sample temperature and wiring

The standard variable temperature insert (VTI) provides sample temperatures in the range 1.5 - 300 K and a clear sample space of 25 mm diameter. Top loading allows samples to be changed while the system is cold and the magnet is at field.

Enhanced sample space
• A modified insert is available that allows measurements on samples up to 30 mm diameter, with a restricted temperature range

3He low temperature option
• HelioxTL.  This 3He insert provides sample temperatures in the range 0.45 - 80 K, supplied either as an alternative to the standard insert or as an interchangeable unit. Changing inserts is an easy operation that takes just a few hours. The sample region has 25 mm diameter access and is fitted with a set of 4 radial Spectrosil B windows in strain-free mounts. The sample rod has a wired 24-way Fischer connector.
A wide range of window materials can be fitted to the Spectromag to meet specific spectroscopy applications

Sample rods
• The standard sample rod permits ±15 mm axial adjustment and full 360° rotation about the vertical axis. There are 3 electrical (Fischer) 10 way connectors, all of which may be pre-wired
• Special sample rods are also available to provide precision movement of the sample about vertical and horizontal axes

Control
• Automatic control using a stepper motor is usually possible
• All standard electronic items are provided with LabVIEW drivers to allow control of the sample temperature and magnetic field. Integration with other virtual instruments provides full experimental control

Special Magnets
Vertical field split pair magnets - These systems have the magnet oriented with the field axis vertical but are otherwise identical to the standard Spectromag. Special systems are also available for Mössbauer spectroscopy with a vertical cooled source/absorber configuration
Horizontal field solenoids with RT bores - The standard Spectromag cryostat may be fitted with an alternative tail set containing a horizontally mounted magnet with a room temperature bore; these are particularly suited to beamline experiments. Standard magnets are available to 11 tesla with 50 mm RT bore; samples can be cooled to 2.7 K using a separate continuous flow cryostat
Vertical field solenoids with axial optical access only - The standard Spectromag cryostat may be fitted with vertical solenoids up to 18 T.  These systems have 1.5 - 300 K inserts provided with one set of Spectrosil B quartz windows in the base. Special systems are also available for Mössbauer spectroscopy with a vertical cooled source/absorber configuration
High homogeneity magnets - For measurements such as optically detected magnetic resonance (ODMR) and electron paramagnetic resonance (EPR), enhanced homogeneity magnets (to 10 ppm) are available.
• Magnetic circular dichroism (MCD)
• Mössbauer and Raman spectroscopy
• Photoluminescence studies
• Faraday effect measurements
• Magneto-optical kerr effect TR- MOKE)

Custom magneto-optical magnet system
Some examples of custom magnets we can provide. Please contact us if you have special requirements.

Vertical field split pair magnets - These systems have the magnet oriented with the field axis vertical but are otherwise identical to the standard Spectromag. Special systems are also available for Mössbauer spectroscopy with a vertical cooled source/absorber configuration
Horizontal field solenoids with RT bores - The standard Spectromag cryostat may be fitted with an alternative tail set containing a horizontally mounted magnet with a room temperature bore; these are particularly suited to beamline experiments. Standard magnets are available to 11 tesla with 50 mm RT bore; samples can be cooled to 2.7 K using a separate continuous flow cryostat
Vertical field solenoids with axial optical access only - The standard Spectromag cryostat may be fitted with vertical solenoids up to 18 T.  These systems have 1.5 - 300 K inserts provided with one set of Spectrosil B quartz windows in the base. Special systems are also available for Mössbauer spectroscopy with a vertical cooled source/absorber configuration
High homogeneity magnets - For measurements such as optically detected magnetic resonance (ODMR) and electron paramagnetic resonance (EPR), enhanced homogeneity magnets (to 10 ppm) are available.
Side-loading sample access
We can provide a custom Spectromag system with side loading as per the picture below allowing optical access into the split bore (ie: perpendicular and parallel to the field) . The sample is mounted on the side loading cold finger, through one of the optical access ports.
A gate valve closes off the cold finger access for sample change. The cold finger, sepparately cooled by continuous flow and can be inserted into either the split ot the bore of the magnet. Please contact us for more details.