Magnetism Of CsCl-type And MgCu₂-type Rare-earth Intermetallic Compounds

The rare-earth intermetallic compounds were attractive due to their good ductility and magnetostrictive property at room temperature. The rare-earth (R) element in the system contains localized f electrons with coupling interactions between spin, obital and lattice, leading to a variety of magnetic properties in this series of materials. For the compound consisted of rare earth and magnetic transiton metal (X), the interaction between R-4/electron and X-3d electron results in more than one type of magnetic order followed by structural defomation, resulting in different physical phenomena like supercooling/superheating, magnetization steps, phase coexistence, kinetic arrest, sluggish relaxation etc. In this doctoral dissertation, we investigate the magnetic properties of the rare-earth compunds with CsCl-type simple cubic structure and MgCu2-type Laves phase one, as well as the influence of doping. The primary contents are as follows,1. We birifly introduce the magnetism of rare earths and transition metals, and the magnetic properties of their compositive intermetallic compounds with CsCl-type simple cubic structure and MgCu2-type Laves phase one through lattice structure, magnetic structure and research status, and then summarize the martensitic scenario in doped CeFe2.2. We constructed the magnetization measurement system and the PDO measurement system under pulsed high magnetic field, and describe their operational principle, structural composition and calibration method, etc. Meanwhile we analyse the noises in signal under pulsed field, and give several methods to improve signal-to-noise ratio.3. The magnetic properties associated with4f electrons in intermetallic RAg (R=Gd, Ho, Dy) compounds with CsCl-type cubic lattice structure were investigated systematically utilizing short-pulse magnet up to50T, to obtain the corresponding magnetic phase diagram. Further, the effect of non-mangeic Al3+substitution for Dy3+on the magnetic behaviors of Dy50-xAlxAgso (x=0,0.3,1.2, and1.8) are studied, with a result of that the sample with highest doping level exhibits quite similar the magnetic behavior with that of the pure DyAg. And we propose a supercell model to give a well interpretation of the observed unusual dilution effect.4. The magnetic transition of DyAg and the upper critical field of a superconductor are measured using the PDO method, compared with the transport and magnetization results of DyAg.5. We investigate the magnetic properties determined by the coupling interaction between localized4f electrons and itinerant3d electrons in Tb0.2Pr0.8(Fe0.4Co0.6)1.93-xCx (x=0,0.05,0.1,0.15,0.2,0.3,0.4, and0.5) intermetallic compounds with MgCu2-type Laves phase. Experimental results reveal that multiple magnetization jumps are observed only in the samples with lower C-concentration (x≤0.2), and the amount of the magnetization steps shows a maximum when x=0.15. The jumps are linked to a disorder-influence first-order magnetostructural phase transition.6. We report detailed magnetic property of the4f-3d quaternary Tb0.2Pr0.8(Fe0.4Co0.6)1.88C0.05compound by dc magnetization measurements. The relaxation time, field sweep rate and cooling field dependence of magnetization jumps resemble the martensite-like scenario.7. We investigate the magnetic properties of Tb1-y Pry(Fe0.4Co0.6)1.88C0.05(y=0,0.8, and1) with different rare earth. Experimental results reveal sharp magnetization jumps can be observed only in the Pr-containing componds.