The Materials Research Science and Engineering Center (MRSEC) “Quantum and Spin Phenomena in Nanomagnetic Structures” (QSPINS) at the University of Nebraska was established in 2002 and renewed in 2008 to carry out collaborative research on new magnetic structures and materials at the nanometer scale, with the aim of developing fundamental understanding of their properties and related phenomena. Nanomagnetic structures have potential applications in areas such as advanced electronics, computing, data storage, energy production, handheld electronic devices, sensors and medical technologies. QSPINS fosters interactions with industrial companies to leverage the expected scientific innovations for potential technological advances.

QSPINS’s research is organized into two IRGs:

IRG 1: Nanoscale Magnetism: Structures, Materials and Phenomena

IRG 2: Magnetoelectric Interfaces and Spin Transport and several seed projects

As an integral part of the Center, QSPINS offers interdisciplinary training for the next generation of materials scientists and engineers by providing regional four-year institutions experience and tools to improve their materials science programs and curricula, offering opportunities for middle- and high-school teachers and their students to learn about materials science, and by addressing pre-college segments of the educational pipeline via targeted outreach activities.

Our shared experimental facilities include Central Facilities operated by the NebraskaCenter for Materials and Nanoscience and Shared Experimental/Computational Facilities associated with this MRSEC.  The Central Facilities are recharge centers with faculty supervisors and materials specialists who maintain equipment and train users. They include electron microscopy, nanofabrication, x-ray materials characterization, crystallography, materials preparation, scanning probe microscopy, and metallurgical and mechanical characterization (http://www.mrsec.unl.edu/facilities/index.shtml).

Details of the IRG’s, seed projects, facilities, and our activities can be found at  www.mrsec.unl.edu. 

SHARED EXPERIMENTAL/COMPUTATIONAL FACILITIES

Shared experimental facilities include Central Facilities operated by the Nebraska Center for Materials and Nanoscience and Shared Experimental/Computational Facilities associated with this MRSEC. 

1. Magnetic Characterization Facilities:

(Supervisor David Sellmyer dsellmyer1@unl.edu, Sy-Hwang Liou sliou1@unl.edu, Roger Kirby rkirby@unlnotes.unl.edu)

These facilities allow measurements of a broad variety of magnetic and magnetooptical properties of materials and include:

1) two Quantum Design SQUID magnetometers (7 T and 5.5 T)
2) Alternating Force Gradient Magnetometer
3) Lakeshore 9T extraction magnetometer and ac susceptometer
4) Lakeshore vibrating sample magnetometer (300 K – 1000 K)
5) two magneto-optic Kerr spectrometers and
6) Zeiss Axiotron Kerr-effect microscope.

Magnetic Characterization Facilities Use/Accessibility: Permission by the faculty supervisors is required to use these facilities.  There are no charges to use these facilities except for operating expenses such as liquid helium and nitrogen. 

2. Electron Spectroscopy Facilities:

(Supervisor Peter Dowben pdowben@unl.edu): 

(1) Spin-polarized inverse photoemission and angle-resolved inverse photoemission facilities at UNL
(2) Spin-polarized photoemission and angle-resolved photoemission facilities at Louisiana Center for Advanced Microstructures and Devices (CAMD) Synchrotron
(3) UV and Soft X-ray CVD facilities and
(4) ESCA and angle-resolved XPS facilities at UNL; high resolution angle-resolved photoemission at Nebraska, spin-polarized electron energy loss at UNL.

The Facilities have the capabilities for angle-resolved photoemission and angle-resolved inverse photoemission as well as spin-polarized inverse photoemission. By using the spin-polarized electron gun sources in conjunction with our large hemispherical analyzer, we have been able to undertake some spin-polarized characteristic electron energy loss spectroscopy.

One of the instrumental “cornerstones” of the electron spectroscopy facilities is the spin-polarized inverse photoemission, spin-polarized scattering system. This instrument is relatively unique. The scalar product of polarization P and the sample magnetization M determines the spin dependence of the measured signals. The system is designed so that the incident spin is transverse (perpendicular) with respect to the incident electron momentum and parallel (or antiparallel) with the applied field for all sample angles, to maximize spin sensitivity.

All of our U.H.V. systems are equipped with reverse view low energy electron diffraction (LEED) and two instruments are equipped with angle-resolved XPS. Angle-resolved XPS with a hemispherical analyzer is routinely used. This facility includes UPS and inverse photoemission and LEED. A load lock/prep chamber is available to outside users.

Electron Spectroscopy Facilities Use/Accessibility:  Access to the 3 m TGM and high-resolution beamlines are undertaken by proposal and scheduling, as managed by the CAMD at Louisiana State University.

The angle-resolved XPS in the Shared Electron Spectroscopy Facility has also been heavily used. Requests must be made (the use of the XPS facility is scheduled). Turn-around time for one sample is two days minimum. The high resolution angle-resolved XPS/spin-polarized IPES and spin scattering facility is also operational, access is not possible in the "non-collaborative" mode.

3. Fast Dynamics Facility:
(Supervisor Roger Kirbyrkirby@unlnotes.unl.edu):

This facility, established by the W. M. Keck Foundation, includes a Coherent Mira 900 femtosecond laser that produces 10 nJ light pulses 150 fs in length at a repetition rate of 76 MHz. The laser output can be tuned over the wavelength range 700 to 900 nm. The repetition rate can be varied from 1 kHz to 27 MHz, at up to 50 nJ pulse energy. Also available is a second harmonic generation unit, which permits the implementation of “two-color” experiments. The optical system is set up in an optical delay line “pump-probe” configuration, with the “probe” pulse being used to measure materials properties at times ranging from 1 ps to 2 ns after the perturbation. A full range of optical components is available, and dedicated optical detectors, amplifiers, choppers, etc. permit a wide variety of measurements.

Fast Dynamics Facility Use/Accessibility: Permission and training by the supervisor of the fast dynamic facilities is required for accessing the shared facility.

4. Computational Facilities:
(Supervisor Kirill Belashchenko kdbel@unlserve.unl.edu)

Beowulf-type clusters including a 112-core 64-bit AMD Opteron machine and a 32-core AMD Athlon MP machine are maintained for calculations of electronic and atomic structure, spin transport, magnetization dynamics, and other tasks. The computer clusters utilize Gigabit Ethernet communication that allows us to perform parallel computations. The available software includes state-of-the-art first-principles density functional codes, molecular dynamics, Monte-Carlo codes, micromagnetic codes, and visualization software.

Computational Facilities Use/Accessibility:  Permission by the supervisor of the computational facilities is required for accessing the shared facilities.

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IRG 2:  Magnetoelectric Interfaces and Spin Transport and several seed projects.