Fundamentals of Magnetism and Magnetic Measurements

Quantum Design QD has only 2 primary product lines Magnetic Property Measurement System (MPMS) Physical Property Measurement System (PPMS) Over 21 years developing an expertise in automated superconducting magnetometers and integrated measurement systems QD is highly respected for its system reliability and service Most systems are used 24 hrs/day, 7 days/week, 365 day/year for many years QD is the recognized leader in automated, high sensitivity magnetic and electrical property measurement systems 669 MPMS and 311 PPMS systems have been installed in leading research centers throughout the world

Quantum Design Magnetic Property Measurement System (MPMS XL™) The Standard for High-Sensitivity Magnetometry

MPMS XL System

MPMS XL EverCool™ System

MPMS XL Overview The MPMS XL offers advanced performance in all areas of magnetometry. Latest design and proven capabilities take SQUID magnetometry to a new level of research Available in 1, 5 and 7 tesla high homogeneity configurations

MPMS XL Benefits Improved measurement sensitivity Increased measurement speed Enhanced temperature control MPMS MultiVu™ WindowsXP Operating System

MPMS XL Temperature Control Patented dual impedance design allows continuous operation below 4.2 K Sample tube thermometry improves temperature accuracy and control Transition through 4.2 K requires no He reservoir refilling and recycling (no pot fills) Temperature sweep mode allows measurements while sweeping temperature at user controlled rate Increases measurement speed Smooth temperature transitions through 4.2 K both cooling and warming

MPMS XL Temperature Control

MPMS XL Temperature Control

MPMS XL Temperature Control Temperature Range: 1.9 - 400 K (800 K with optional oven) Operation Below 4.2 K: Continuous Temperature Stability: ±0.5% Sweep Rate Range: 0.01 - 10 K/min with smooth transitions through 4.2 K Temperature Calibration ±0.5% typical Accuracy: Number of Thermometers: 2 (one at bottom of sample tube; one at the location of sample measurements)

Magnetic Field Control Very high homogeneity magnets (1, 5 and 7 Tesla) 0.01% uniformity over 4 cm Magnets can be operated in persistent or driven mode Hysteresis mode allows faster hysteresis loop measurements Magnets have two operating resolutions: standard and high resolution

Hysteresis Measurement

Reciprocating Sample Measurement System (RSO) Improved measurement sensitivity Increased measurement speed No waiting for the SQUID to stabilize Very fast hysteresis loops up to 8x faster than conventional MPMS Servo motor powered sample transport allows precision oscillating sample motion High precision data acquisition electronics includes a digital signal processor (DSP) SQUID signal phase locked to sample motion Improved signal-to-noise ration Low thermal expansion sample rods with sample centering feature

Reciprocating Sample Measurement System (RSO)

RSO Data The DC scan took 56 hours to take 960 points The RSO scan took 1600 points in under 24 hours! The RSO scan avoids subjecting the sample to field inhomogeneities that effected the DC scan.

RSO Data The system stayed below 4.2 K for 30 hours to acquire a measurement every 100 Oe up to and down from 5 tesla By moving the sample only 0.5 mm using RSO, the sample was exposed to very little field inhomogeneity.

RSO Data The system stayed below 4.2 K for 33 hours to perform these hysteresis measurements in a single sequence There are 3350 data points in this graph

Hysteresis Mode Data This measurement takes ~ 3.5 hours in persistent mode

Reciprocating Sample Measurement System (RSO) Frequency Range: 0.5 - 4 Hz Oscillation Amplitude: 0.5 - 50 mm Relative Sensitivity: < 1 x 10-8 emu; H  2,500 Oe, T = 100 K (for 7-tesla magnet)  6 x 10-7 emu; H @ 7 tesla, T = 100 K (for 7-tesla magnet) Dynamic range 10-8 to 5 emu (300 emu with Extended Dynamic Range option)

MPMS MultiVu Control Software MS WindowsXP-based - pull down menus and mouse control Simultaneous access to all aspects of system operation Multiple documents and views visible and useable at the same time Simultaneous display of data files in multiple formats Simplified, more powerful, measurement sequence editor Automatic Background Subtraction routine

MPMS MultiVu Control Software

MPMS System Options Transverse Moment Detection for examining anisotropic effects Second SQUID detection system SQUID AC Susceptibility 2 x 10-8 emu sensitivity 0.1 Hz to 1 kHz Ultra-Low Field Reduce remanent magnet field to < 0.05 Oe Extended Dynamic Range Measure moments to ±300 emu External Device Control Control user instruments with the MPMS Sample Rotators Vertical and Horizontal Sample Space Oven Temperatures to 800 K Environmental Magnetic Shields Fiber Optic Sample Holder Allows sample excitation with light Manual Insertion Utility Probe Perform elector-transport measurements in MPMS Liquid Nitrogen Shielded Dewar EverCool Cryocooled Dewar No-Loss liquid helium dewar No helium transfers

Transverse Moment Detection Measures anisotropic effects of moments with vector components perpendicular to the applied field Incorporates a second SQUID detection system which can resolve transverse moments as small as 10-6 emu Second-order detection coils orthogonal to the longitudinal detection coils

SQUID AC Susceptibility Dynamic measurement of sample Looks also at the resistance and conductance Can be more sensitive the DC measurement Measures Real () and Imaginary () components  is the resistance of the sample  is the conductive part Proportional to the energy dissipation in the sample Must resolve components of sample moment that is out of phase with the applied AC field SQUID is the best for this because it offers a signal response that is virtually flat from 0.01 Hz to 1 kHz Available on all MPMS XL systems Requires system to be returned to factory for upgrade

SQUID AC Susceptibility Features Programmable Waveform Synthesizer and high-speed Analog-to-Digital converter AC susceptibility measured automatically and can be done in combination with the DC measurement Determination of both real and imaginary components of the sample’s susceptibility Frequency independent sensitivity Specifications Sensitivity (0.1 Hz to 1 kHz): 2 x 10-8 emu @ 0 Tesla 1 x 10-7 emu @ 7 Tesla AC Frequency Range: 0.01 Hz to 1 kHz AC Field Range: 0.0001 to 5 Oe (system dependent) DC Applied Field: 0.0005 to 70 kOe (system dependent)

SQUID AC Susceptibility

Ultra-Low Field Capability Actively cancels remanent field in all MPMS superconducting magnets Sample space fields as low as 0.005 Oe achievable Custom-designed fluxgate magnetometer supplied Includes Magnet Reset Requires the Environmental Magnet Shield

Hysteresis measurement

Extended Dynamic Range Extends the maximum measurable moment from ± 5 emu to ± 300 emu (10 orders of magnitude) Automatically selected when needed in measurement Effective on both longitudinal and transverse SQUID systems

Sample Space Oven Provides high temperature measurement capability Ambient to 800 K Easily installed and removed by the user when needed A minimal increase in helium usage Approximately 0.1 liters liquid helium/hour 3.5 mm diameter sample space

MPMS Horizontal Rotator Automatically rotates sample about a horizontal axis during magnetic measurement 360 degrees of rotation; 0.1 degree steps Sample platform is 1.6 X 5.8 Diamagnetic background signal of 10-3 emu at 5 tesla

Manual Insertion Utility Probe Perform electro-transport measurement in the MPMS sample space 10-pin connector Use with External Device Control (EDC) for controlling external devices (e.g., voltmeter and current source) Creates fully automated electro-transport measurement system

External Device Control Allows control and data read back from third party electronics Allows custom control of MPMS electronics Use with Manual Insertion Utility Probe for automated electro-transport measurements MPMS MultiVu version written in Borland’s Delphi (Visual Pascal) programming language

Hysteresis Measurement made with External Device Control (EDC) Using EDC to control a DC field using the AC coil in the MPMS Up to ± 8 Oe DC field (system dependent) Step size as small as 1.9 Oe 20 Å Ni Thin Film (PSI, Zurich)

Fiber Optic Sample Holder Allows sample to be illuminated by an external light source while making magnetic measurements Optimized for near UV spectrum (180 to 700 nm) Includes 2-meter fiber optic bundle Sample bucket 1.6 mm diameter and 1.6 mm deep Slide seal Fiber optic bundle SMA connector

MPMS Liquid Helium Dewar Options Basic system supplied with a vapor shielded 56 liter dewar Liquid nitrogen jacketed version of the basic dewar improves hold time by ~ 30% MPMS EverCool Cryocooled Dewar

MPMS EverCool Dewar Designed to eliminate the need for liquid helium transfers Virtually eliminates all helium loss from the Quantum Design MPMS magnetometer system Cryocooler-dewar system that recondenses the helium directly in the dewar Integrated into MPMS Operating System Cryocooler operation can be controlled automatically to minimize interference with sensitive magnetic measurements Available as an upgrade to all MPMS systems (no equipment needs to be returned to Quantum Design) Available with water or air cooled compressor

MPMS EverCool Dewar Cryocooler coldhead Liquid helium condenser unit

MPMS EverCool Dewar

MPMS MultiVu™ Control Software MPMS MultiVu Windows-based control software takes full advantage of MicroSoft’s Multi Document Interface (MDI) User friendly environment using common Windows protocols All system and measurement operations controlled using pull-down menus Provides the ability to observe multiple data graphs to compare old data with data begin acquired Each user can set their own measurement sequences and data files so experimental set-ups and data are safe on the multi-user system Remote operation of the system and remote service capability with MPMS computer connected to Internet WindowsXP version available End of 2002

MPMS MultiVu Control Software

MPMS MultiVu Control Software

System Installation and Acceptance Every MPMS sale includes complete system installation and customer training Up to 5 days During the installation, the system will be tested to meet a set number of specifications

Currently in Development: High Pressure Cell Manufactured by easyLab Limited in the UK Offers 10 kbar of pressure Supplied with complete user’s kit

Quantum Design MPMS Designed For Scientists, By Scientists

A Brief History of Superconductivity

The Chronology 1911 – Heike Kammerlingh Onnes discovers superconductivity 1913 Receives the Nobel Prize in Physics 1962 – Brian Josephson predicts the “Josephson Effect” 1973 Receives the Nobel Prize in Physics 1986 – Bednorz and Muller discover High Temperature Superconductivity 1987 They receive the Nobel Prize in Physics

The SQUID Within a year of Brian Josephson’s discovery, the first Superconducting Quantum Interference Device (SQUID) was built In 1968, Professor John Wheatley of UCSD and four other international physicists founded S. H. E. Corp. (Superconducting Helium Electronics) to commercialize this new technology.

SQUID Magnetometers The first SQUID magnetometer was developed by Mike Simmonds, Ph.D. and Ron Sager, Ph.D. while at S.H.E. Corporation in 1976. In 1982, Mike and Ron, along with two other SHE employees, founded Quantum Design. In 1984, QD began to market the next generation SQUID magnetometer – the Magnetic Property Measurement System (MPMS). In 1996, QD introduced the MPMS XL as the latest generation SQUID magnetometer During the past 18 years, six companies have design and marketed SQUID magnetometers to compete with the MPMS. Of these only one still exists – Cryogenic Limited in the UK.

The Superconducting Components The superconducting magnet The superconducting detection coil The Superconducting QUantum Interference Device (SQUID) The superconducting magnetic shield surrounding the SQUID

The SQUID System The Superconducting QUantum Interference Device (SQUID) give the MPMS is the source of the instrument’s sensitivity Extremely sensitive current-to-voltage converter Sample moving through the superconducting detection coils induces a small current in the coils SQUID output voltage is proportional to the magnet moment of the sample

The Detection Coil The MPMS XL uses a second-order gradiometer configuration Positioned at the center of the magnetic field Reduces noise from uniform distance sources Part of a closed superconducting loop