Jenniffer Roames and Tim Young
The University of Memphis
April 12th, 2006, 4:00pm, Manning Hall 201
Refreshments served at 3:30pm, Manning Hall 222
TRACE: Isothermal "Eyes" Only?
Even though the Sun is the most studied star, we do not know everything about it.
One unanswered question is the “coronal heating problem.” The surface of the Sun is
approximately 5800 K. However, the solar atmosphere (corona) extends more than a million
kilometers from the surface of the Sun and reaches temperatures greater than 1,000,000
K. There are many theories as to how the corona is heated. One is by studying the
temperature along coronal loops that are formed when plasma follows the twisted magnetic
field of the Sun.
The loops extend many thousands of kilometers above the Sun’s surface. To support
these theories it must be determined whether these loops are preferentially heated
at the footpoints or the apex. The Transition Region and Coronal Explorer (TRACE)
has provided many spectacular images of these solar loops. TRACE also has the ability
to calculate temperature along these loop structures. After studying many TRACE loops
our data gave us the same answer every time. Which was that each loop had the same
temperature, 1.2 MK. An important question is why is the temperature always the same?
Tune in to find out the answer.
Core-shell Ferromagnetic-Antiferromagnetic Nanocomposite
Permanent magnetic materials currently available in the market are based on the rare
earth transition metal alloys such as Sm2Fe17Nx and Nd2Fe14B. The strength of the
magnet, energy product (BHmax), is defined by the maximum area under the second quadrant
of the hysteresis loop; i.e. squarness of the loop. Thus, an increase in the strength
of the magnet can be brought in by increasing the coercivity and remanence of the
In theory coercivity and remanence enhancement for a magnetic material is possible
via exchange bias interaction between ferromagnetic (FM) and antiferromagnetic (AFM)
phases in contact. We have synthesized core-shell ferromagnetic-antiferromagnetic
nanocomposite, Fe2O3 (FM)-NiO (AFM) material via hydrothermal synthesis technique.
Details of the structural measurements including XRD, TGA and TEM along with magnetization
measurements will be presented. The magnetization measurements indeed show an increase
in the coercivity and the remanence of Fe2O3-NiO composite.
Encouraged by these results we are in a process of synthesizing Sm2Fe17Nx-NiO/CoO
nanocomposite magnets. Our research has great industrial significance because FM-AFM
nanocomposites will use less rare-earth element compared to pure Sm2Fe17Nx but still
be able to maintain high energy product. This will reduce the cost of magnet and increase
their environmental stability.