Quantum Design's Magnetic Property Measurement System (MPMS) is a suite of analytical instruments designed to study the magnetic properties of experimental samples. Measurements can be automated and performed across a range of temperature and magnetic field strengths. Although this and the DynaCool™ share some functional overlap the MPMS instrument can obtain higher resolution measurements using a Superconducting Quantum Interference Device (SQUID) in combination with superconducting pickup coils. The system is also capable of much faster field charging and temperature cooling rates.
Experimental samples are first mounted and centered in a magnetically neutral medium. High quality materials, such as quartz tubing, are available but these are often brittle or fragile. For less sensitive measurements a more robust approach utilizes drinking straws that have been tested for magnetic impurities. Once mounted the sample holder is sealed and connected to a rod before being lowered into the sample probe.
How it works:
When a measurement begins the linear transport motor, which sits atop the sample probe, begins driving the sample up and down through a region of the chamber surrounded by super conducting coils. As a magnetic sample moves up and down through the detection coils it creates magnetic flux and induces an electrical current. The detection coils form a closed loop with the SQUID component. The induction of a current across this closed circuit, in response to the sample, is proportional to the magnetic flux.
The SQUID's Role
The SQUID functions as a highly linear current-to-voltage convertor through the use of two parallel Josephson junctions separated by thin insulating layers. The device itself built on a small chip and seated at the bottom of the sample probe. This circuit is highly sensitive to magnetic field fluctuations and must be heavily shielded to reduce noise.
|Range:||1.8 to 400 K Standard; 1.8 to 1000 K with Oven option|
|Cooling Rate:||30 K/min (300 to 10 K in 15 minutes)|
|10 K/min (10 to 1.8 K in 5 minutes)|
|Range:||-70 kOe to +70 kOe|
|Charging Rate:||4 Oe/sec to 700 Oe/sec|
|Uniformity:||±0.01% over 4 cm on axis|
|Charging Resolution:||0.33 Oe|
|Maximum DC moment:||10 emu|
(≤ 2,500 Oe):
|≤ 5 x 10-8 emu (DC scan)|
|≤ 1 x 10-8 emu (VSM, less than 10 second averaging)*|
(> 2,500 Oe):
|≤ 6 x 10-7 emu (DC scan)|
|≤ 8 x 10-8 emu (VSM, less than 10 second averaging)*|
|Variable drive amplitude:||0.1 to 8 mm (peak)|
|Measurement Options:||VSM EverCool, VSM Oven (1000 K), AC option|
|Sample Chamber Size:||Inner Diameter of 9 mm|
Related research publications using this instrument
- Deciphering structural and magnetic disorder in the chiral skyrmion host materials CoxZnyMnz (x+y+z=20)
- High-Pressure Laser Floating Zone Furnace
- Low magnetic damping and large negative anisotropic magnetoresistance in half-metallic Co2-xMn1+xSi Heusler alloy films grown by molecular beam epitaxy
The SQUID MPMS3 instrument is located in the Low-Temperature Lab, Room 1055, at the Materials Research Lab
The manufacturer's description is posted at https://qdusa.com/products/mpms3.html
Instrument Information and/or Manual:
|MPMS3 Users Manual||6.44 MB|
|VSM AC Option Manual||3.47 MB|
|VSM Oven Option Manual||882.89 KB|
|High Temperature AC Measurement Applications Notes||303.86 KB|
|Fundamentals of Magnetism for MPMS||8.55 MB|
To request training or inquire about sending samples please contact amanda [at] mrl [dot] ucsb [dot] edu (Amanda Strom) or seshadri [at] mrl [dot] ucsb [dot] edu (Ram Seshadri).