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Quantum Design’s new SQUID-based VSM
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The SQUID VSM extends the popular family of the „Magnetic Property Measurement Systems“ (MPMS®) from Quantum Design.
The system offers the user a very high sensitivity (≤ 10-8 emu) at high measurement speed. The instrument uses a linear motor to drive the samples through the pick-up coils of a SQUID gradiometer. In conjunction with a newly developed superconducting switch it is possible to do DC-SQUID measurements approx. 10 times faster than it was possible up to now.
This means that a much higher sample throughput can be achieved. So the costs for liquid helium per measurement point are drastically reduced and make the instrument very attractive in respect of the price/performance ratio. |
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Data Aquisition:
The FastLab™ data acquisition combines Quantum Design’s dc SQUID sensor and novel Vibrating Sample Magnetometer technology thus providing the ability to achieve <1 x 10-8 emu sensitivity at zero magnet field with 4-second data averaging. Further noise reduction in the design allows this system to achieve an unprecedented <5 x 10-8 emu sensitivity with 4 second averaging at the full field of 7 tesla.
The diameter of the temperature control insert was selected to allow a 9 mm sample bore and to provide the smallest diameter pickup coils possible to optimize the magnetometer’s sensitivity.
Temperature Control:
The MPMS SQUID VSM uses the newly designed RapidTemp™ innovative temperature control design that allows the user to cool samples from room temperature to a stable 1.8 K in 30 minutes. The temperature control insert of the MPMS SQUID VSM uses a finely tuned flow impedance and sophisticated temperature control software to provide continuous operation at 1.8 K as well as smooth temperature control through the 4.2 K liquid helium boiling point. Heaters on the sample chamber can raise the temperature as high as 400 K. A thermal shield, anchored to a liquid nitrogen tank of the dewar, intercepts heat from a warm sample chamber and minimizes consumption of liquid helium when operating at higher temperatures.
Magnet Control:
The MPMS SQUID VSM utilizes a 7 Tesla, superconducting, helium-cooled magnet and a magnet controller designed specifically for the SQUID VSM to achieve precise, quiet control of the magnetic field. The SQUID VSM employs a unique superconducting switching element called the QuickSwitch™ (patent pending), which changes between superconducting and normal states in under one second. This allows rapid collection of high precision data. The QuickSwitch™ design also helps to minimize liquid helium consumption when ramping magnetic field, as compared to more traditional superconducting persistent switch technology. Further aiding the instrument’s low helium consumption is the use of high temperature superconductor (HTS) magnet leads anchored to a liquid nitrogen tank. The nitrogen shield in this design absorbs a great deal of room temperature heat that would otherwise be conducted to the helium bath. |
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| Basic System Specifications: |
| Temperatur Range: |
1,8 K – 400 K |
| Sample Chamber I.D.: |
9 mm |
| Magnetic Field Range: |
± 70 kOe |
| Maximum DC moment: |
10 emu |
| Sensitivity: |
< 1*10-8 emu at zero field (4 sec. averaging)
< 5*10-8 emu at 70 kOe (4 sec. averaging) |
| A fast scan of the moment versus field at 5 K is shown for a thin film ferromagnetic sample provided by Professor Eckert of Harvey Mudd College. The insert illustrates the speed of the measurement process and the higher resolution data at the lower fields. |
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