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Full-Text Articles in Physics

Magnetism Of (Dy0.5er0.5)Al2 Single Crystal In Ac And Dc Magnetic Fields, Evgenii M. Levin, Karl A. Gschneidner Jr., Thomas A. Lograsso, Deborah L. Schlagel Aug 2006

Magnetism Of (Dy0.5er0.5)Al2 Single Crystal In Ac And Dc Magnetic Fields, Evgenii M. Levin, Karl A. Gschneidner Jr., Thomas A. Lograsso, Deborah L. Schlagel

Ames Laboratory Publications

The temperature (4.2–90 K), ac magnetic field (1.25–50 Oe), frequency (5–125 Hz), and bias dc magnetic field (0–10 kOe) dependencies of the real and imaginary components of the ac magnetic susceptibility, and the temperature (4.2–250 K) and dc magnetic field(0.1–50 kOe) dependencies of the dc magnetic susceptibility and magnetization of a(Dy0.5Er0.5)Al2 single crystal have been studied. Isothermal magnetization measurement in a dc magnetic field indicates that (Dy0.5Er0.5)Al2 orders ferromagnetically at 37 K. The ac ...


Fe–Ga/Pb(Mg1/3nb2/3)O3–Pbtio3 Magnetoelectric Laminate Composites, Shuxiang Dong, Junyi Zhai, Naigang Wang, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso Nov 2005

Fe–Ga/Pb(Mg1/3nb2/3)O3–Pbtio3 Magnetoelectric Laminate Composites, Shuxiang Dong, Junyi Zhai, Naigang Wang, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso

Ames Laboratory Publications

We have found large magnetoelectric (ME) effects in long-type laminate composites of Fe–20%Ga magnetostrictive alloys and piezoelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals. At lower frequencies, the ME voltage coefficient of a laminate with longitudinally magnetized and longitudinally polarized (i.e., L-L mode) layers was 1.41 V/Oe (or1.01 V/cm Oe). Near the natural resonant frequency ( ∼ 91 kHz) of the laminate, the ME voltage coefficients were found to be dramatically increased to 50.7 V/Oe (36.2 V/cm Oe)for the L-L mode. In ...


Magnetic Force Microscopy Investigation Of Domain Structures In Fe–X At. % Ga Single Crystals (12, Feiming Bai, Jiefang Li, D. Viehland, D. Wu, Thomas A. Lograsso Jul 2005

Magnetic Force Microscopy Investigation Of Domain Structures In Fe–X At. % Ga Single Crystals (12, Feiming Bai, Jiefang Li, D. Viehland, D. Wu, Thomas A. Lograsso

Ames Laboratory Publications

The domain structure of furnace-cooled (FC) and post-annealed (PA) Fe–x at. % Ga (x = 12, 20, and 25) crystals has been investigated by magnetic force microscopy. For both FC and PA Fe–12 at. % Ga, the domains were found to be well-aligned and oriented along the [100] direction. For Fe–20 at. % Ga, although a preferred [100] orientation remained, a difference in morphology was found between FC and PA conditions—in the PA condition, clear dendritic domains were observed. For both FC and PA Fe–25 at. % Ga, a much reduced [100] preferred domain orientation was found, the domain size ...


Magnetostrictive And Magnetoelectric Behavior Of Fe–20 At. % Ga/Pb(Zr,Ti)O3 Laminates, Shuxiang Dong, Junyi Zhai, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso Apr 2005

Magnetostrictive And Magnetoelectric Behavior Of Fe–20 At. % Ga/Pb(Zr,Ti)O3 Laminates, Shuxiang Dong, Junyi Zhai, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso

Ames Laboratory Publications

The magnetostrictive and magnetoelectric (ME) properties of laminate composites of Fe–20 at. % Ga and Pb(Zr,Ti)O3 (PZT) have been studied for laminates of different geometries. The results show that (i) a long-type magnetostrictive Fe–20 at. % Ga crystal plate oriented along 〈001〉c and magnetized in its longitudinal (or length) direction has higher magnetostriction than a disk-type one; and consequently (ii) a long-type Fe–20 at. % Ga/PZT laminate has a giant ME effect, and is sensitive to low-level magnetic fields.


Magnetism, Elasticity, And Magnetostriction Of Fecoga Alloys, Liyang Dai, James Cullen, Manfred Wuttig, Thomas A. Lograsso, Eckhard Quandt May 2003

Magnetism, Elasticity, And Magnetostriction Of Fecoga Alloys, Liyang Dai, James Cullen, Manfred Wuttig, Thomas A. Lograsso, Eckhard Quandt

Ames Laboratory Publications

It is known that the substitution of Co for Fe gives rise to increases in magnetization and Curie temperature, not only in the bcc metals, but also in intermetallic compounds and alloys as well. With the expectation that this is the case in Co-substituted FeGa, we measured magnetization, Curie temperature, magnetostriction and elastic constants of a series of polycrystalline FeCoGa ternary alloys with up to 17% Ga and up to 10% Co. The magnetostriction at saturation for Fe0.93−xCo.07Gax increases to 90 ppm for x=0.17. For larger percentages of Co, the rise ...


Magnetostriction Of Ternary Fe–Ga–X Alloys (X=Ni,Mo,Sn,Al), J. B. Restorff, M. Wun-Fogle, A. E. Clark, Thomas A. Lograsso, A. R. Ross, Deborah L. Schlagel May 2002

Magnetostriction Of Ternary Fe–Ga–X Alloys (X=Ni,Mo,Sn,Al), J. B. Restorff, M. Wun-Fogle, A. E. Clark, Thomas A. Lograsso, A. R. Ross, Deborah L. Schlagel

Ames Laboratory Publications

Investigations were made into the effect of small additions of Ni, Mo, Sn, as well as larger additions of Al on the magnetostriction of single crystal Fe100−xGax alloys (x≅13). The Fe–Ga and Fe–Al systems are seemingly unique among the Fe-based alloys in having very large magnetostrictions in spite of Ga and Al being nonmagnetic. In this paper, we show how additions of Ni, Mo, Sn, and Al affect λ100 and λ111 of the binary Fe–Ga alloys. We substituted small amounts of Ni into a binary Fe–Ga alloy in an ...


6% Magnetic-Field-Induced Strain By Twin-Boundary Motion In Ferromagnetic Ni–Mn–Ga, S. J. Murray, M. Marioni, S. M. Allen, R. C. O'Handley, Thomas A. Lograsso Aug 2000

6% Magnetic-Field-Induced Strain By Twin-Boundary Motion In Ferromagnetic Ni–Mn–Ga, S. J. Murray, M. Marioni, S. M. Allen, R. C. O'Handley, Thomas A. Lograsso

Ames Laboratory Publications

Field-induced strains of 6% are reported in ferromagnetic Ni–Mn–Ga martensites at room temperature. The strains are the result of twin boundary motion driven largely by the Zeeman energy difference across the twin boundary. The strain measured parallel to the applied magnetic field is negative in the sample/field geometry used here. The strain saturates in fields of order 400 kA/m and is blocked by a compressive stress of order 2 MPa applied orthogonal to the magnetic field. The strain versus field curves exhibit appreciable hysteresis associated with the motion of the twin boundaries. A simple model accounts ...


Recent Developments In Modeling Of The Stress Derivative Of Magnetization In Ferromagnetic Materials, David C. Jiles, Michael K. Devine Nov 1994

Recent Developments In Modeling Of The Stress Derivative Of Magnetization In Ferromagnetic Materials, David C. Jiles, Michael K. Devine

Ames Laboratory Publications

The effect of changing stress on the magnetization of ferromagnetic materials leads to behavior in which the magnetization may increase, or decrease, when exposed to the same stress under the same external conditions. A simple empirical law seems to govern the behavior when the magnetization begins from a major hysteresis loop. The application of the law of approach, in which the derivative of the magnetization with respect to the elastic energy supplied dM/dW is proportional to the magnetization displacement M anM, is discussed.