Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic NiMnGa Single Crystal.

Magnetic hysteresis is a manifestation of non-equilibrium state of magnetic domain walls trapped in local energy minima. Using two types of experiments we show that, after application of a magnetic field to a ferromagnet, acoustic oscillations excited in the latter can "equilibrate" metastable magnetic domain structure by triggering the motion of domain walls into more stable configurations. Single crystals of archetypal NiMnGa magnetic shape memory alloy in the cubic phase were used in the experiments.

Structure, Martensitic Transformation, and Damping Properties of Functionally Graded NiTi Shape Memory Alloys Fabricated by Laser Powder Bed Fusion.

Besides the unique shape memory effect and superelasticity, NiTi alloys also show excellent damping properties. However, the high damping effect is highly temperature-dependent, and only exists during cooling or heating over the temperature range where martensitic transformation occurs. As a result, expanding the temperature range of martensite transformation is an effective approach to widen the working temperature window with high damping performance.

Domain Dynamics in Quantum-Paraelectric SrTiO_{3}.

Twin dynamics forced by acoustic waves shows several linear and nonlinear response modes below T_{c}=106  K. In the quantum paraelectric state a "quantum domain glass" at 25  K View Article and Find Full Text PDF

Author Correction: Temperature Chaos, Memory Effect, and Domain Fluctuations in the Spiral Antiferromagnet Dy.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Temperature Chaos, Memory Effect, and Domain Fluctuations in the Spiral Antiferromagnet Dy.

The spiral antiferromagnetic phase of polycrystalline dysprosium between 140 K and the Néel temperature at 178 K and its domain wall (DW) dynamics were investigated using high-resolution ultrasonic spectroscopy. Two kinetic processes of quasi-static DW motion occur under non-isothermal and isothermal conditions. A "fast" process is proportional to the rate of the temperature change and results in a new category of anelastic phenomena: magnetic transient ultrasonic internal friction (IF).

Magnetic Domain Walls and Macroscopic Magnetization-Related Elastic and Anelastic Effects during Premartensitic Transition in Ni₂MnGa.

The temperature and field dependences of internal friction and Young´s modulus are studied using a high-resolution ultrasonic (90 kHz) technique in stoichiometric ferromagnetic Ni₂MnGa shape memory alloy close to the premartensitic transformation temperature, , in the demagnetized state and under moderate fields. Several new effects observed like an apparent Young´s modulus softening close to under moderate fields, instead of the hardening outside this range, as well as existing controversies in the apparent elastic and anelastic properties of Ni₂MnGa close to are explained by microeddy and macroeddy current relaxations that to date have been disregarded.

A Short Review on the Microstructure, Transformation Behavior and Functional Properties of NiTi Shape Memory Alloys Fabricated by Selective Laser Melting.

Due to unique functional and mechanical properties, NiTi shape memory alloys are one of the most promising metallic functional materials. However, the poor workability limits the extensive utilization of NiTi alloys as components of complex shapes. The emerging additive manufacturing techniques provide high degrees of freedom to fabricate complex structures.

On the Effect of Hydrogen on the Low-Temperature Elastic and Anelastic Properties of Ni-Ti-Based Alloys.

Linear and non-linear internal friction and the effective Young's modulus of a NiTi alloy have been studied after different heat treatments, affecting hydrogen content, over wide ranges of temperatures (13-300 K) and strain amplitudes (10-10) at frequencies near 90 kHz. It has been shown that the contamination of the alloy by hydrogen strongly affects the internal friction and Young's modulus of the martensitic phase. Presence of hydrogen gives rise to a non-relaxation internal friction maximum due to a competition of two different temperature-dependent processes.

Direct observation of polar tweed in LaAlO3.

Polar tweed was discovered in mechanically stressed LaAlO3. Local patches of strained material (diameter ca. 5 μm) form interwoven patterns seen in birefringence images, Piezo-Force Microscopy (PFM) and Resonant Piezoelectric Spectroscopy (RPS).

A new Y chromosome marker for noninvasive fetal gender determination.

We have developed a real-time PCR assay for early fetal gender diagnostics based on the analysis of the Y chromosome-specific multicopy DAZ sequence in the circulating DNA from maternal blood. One fluorescent probe and two pairs of primers used simultaneously in one PCR reaction make it possible to detect as little as 1.5 x 10(-6) ng of DNA isolated from male plasma.