S. Lin

Phase‐matching retracing behavior: New features in LiB3O5

Retraces of phase‐matching (PM) angles and noncritical phase‐matching temperatures for both type I and type II second harmonic generation in LiB3O5(LBO) are first demonstrated. By fitting to the measured PM angles at room temperature, new Sellmeier’s equations of LBO are obtained. Further analyzing the spectral and angle acceptances, we point out that LBO is particularly useful in doubling radiations near 1.3 μm such as 1.32 μm of Nd:YAG, 1.31 μm of Nd:YLF, and 1.34 μm of Nd:YAP.

Tunable negative thermal expansion related with the gradual evolution of antiferromagnetic ordering in antiperovskite manganese nitrides Ag1−xNMn3+x (0 ≤ x ≤ 0.6)

The thermal expansion and magnetic properties of antiperovskite manganese nitrides Ag1-xNMn3+x were reported. The substitution of Mn for Ag effectively broadens the temperature range of negative thermal expansion and drives it to cryogenic temperatures. As x increases, the paramagnetic (PM) to antiferromagnetic (AFM) phase transition temperature (TN) decreases. At x~0.2, the PM-AFM transition overlaps with the AFM to glass-like state transition. Above x=0.2, two new distinct magnetic transitions were observed: one occurs above room temperature from PM to ferromagnetic (FM), and the other one evolves at a lower temperature (T*) below which both AFM and FM orderings are involved. Further electron spin resonance measurement suggests that the broadened volume change near T* is closely related with the evolution of {\Gamma}5g AFM ordering.

Magnetic and electrical/thermal transport properties of Mn-doped Mn+1AXn phase compounds Cr2-xMnxGaC (0 《 x 《 1)

In this paper, we report the effects of partial substitution of Mn for Cr on the structural, magnetic, and electrical/thermal transport properties of Mn+1AXn phase compounds Cr2−xMnxGaC (0 ≤ x ≤ 1). As a result, the unit cell volume and the thermal conductivity decrease while the resistivity increases with increasing x. Interestingly, the magnetism of Cr2−xMnxGaC changes from the nonmagnetic Cr2GaC (x = 0) to the ferrimagnetic CrMnGaC (x = 1). In order to shed light on the discrepancy observed between Hall coefficient and Seebeck coefficient of Cr2GaC, the electrical conductivity, Hall coefficient, and magnetoresistance are analyzed within a two-band model. Furthermore, an upturn is observed in low-temperature specific heat of Cr2−xMnxGaC, which may be related with the magnetic Mn dopant.

The magnetic, electrical transport and thermal transport properties of Fe-based antipervoskite compounds ZnCxFe3

The effects of carbon concentration on the crystal structure, magnetic, and electrical/thermal transport properties of ZnCxFe3 (1.0 ≤ x ≤ 1.5) have been investigated systematically. Both the Curie temperature and the saturated magnetization decrease firstly and then reach saturation with increasing x. The investigations of heat capacity and resistivity indicate that ZnC1.2Fe3 displays a strongly correlated Fermi liquid behavior considering its Kadowaki-Woods ratio (∼0.64 a0). Around the ferromagnetic-paramagnetic phase transition (∼358 K), a reversible room-temperature magnetocaloric effect is observed. The relative cooling power (RCP) is ∼164 J/kg (∼385 J/kg) with the magnetic field change ΔH = 20 kOe (45 kOe). Considering the considerable large RCP, inexpensive and innoxious raw materials, ZnC1.2Fe3 is suggested to be a promising candidate for room-temperature magnetic refrigeration. Furthermore, the studies of thermal transport properties indicate that ZnC1.2Fe3 can also be a potential thermoelectric m...

Composition dependent-magnetocaloric effect and low room-temperature coefficient of resistivity study of iron-based antiperovskite compounds Sn1−xGaxCFe3 (0 ≤ x ≤ 1.0)

We present the magnetic/structural phase diagram of Sn1-xGaxCFe3 (0 ≤ x ≤ 1). With increasing x, Curie temperature (TC) and saturated magnetization increase while lattice constant decreases. The results indicate that GaCFe3 may be a promising high-temperature soft magnetic material. Around TC, chemical composition-dependent magnetocaloric effect is studied. The relative cooling power increases with increasing x, reaching a maximum of ∼3.22 J/cm3 (∼61% of Gd) around 345 K. Considering their remarkable advantages, Sn1-xGaxCFe3 are suggested to be promising magnetic refrigerant materials. The low-T resistivity displays a metallic behavior for x ≤ 0.80 and a semiconductor-like behavior for GaCFe3. Furthermore, room-temperature coefficient of resistivity is comparative (∼46.2 ppm/K for GaCFe3, 250-310 K).

Phase matching retracing behavior for second harmonic generation in LiB3O5 crystal

The nonmonotonic relation between the increasing wavelength and the noncritical phasematching (NCPM) temperature are analyzed in detail for temperature‐tuned as well as the phase matching angle for angle‐tuned second harmonic generation in a LiB3O5 (LBO) crystal. This relation was called ‘‘the phase matching retracing behavior.’’ Because of the retrace, LBO is the unique nonlinear optical crystal that can produce the spectra through blue to near infrared by NCPM. It has been shown that the retracing wavelengths (∼1.3 μm), and furthermore, the conjugation relation for phase matched wavelengths are approximately independent of the tuning means. There exist at the retracing wavelengths not only the retrace for the tuning curves but also for the beam walkoff, group velocity mismatch, and the angular and spectral acceptances. The spectral noncritical phase matching is achieved and the group velocity mismatch is zero at the retracing points. The temperature acceptances are also very large. These properties of L...

Metastability across the antiferromagnetic–ferromagnetic intermediate phase transition and enhanced giant magnetoresistance in Zn-doped antiperovskite compounds Ga1−xZnxCMn3

We report the detailed investigations of the magnetic properties, electronic transport, and specific heat in Zn-doped antiperovskite compounds Ga1−xZnxCMn3. Magnetic measurements indicate the metastability of the antiferromagnetic (AFM)–ferromagnetic intermediate (FI) phase transition and the coexistence of different magnetic phases at lower temperature. The enhanced giant magnetoresistance (GMR) is observed with a maximum value of 70% spanning a temperature range of 100 K at 50 kOe. The analysis of heat capacity reveals that the metastability of the AFM–FI transition and the enhanced GMR observed in Ga1−xZnxCMn3 may originate from the reconstruction of Fermi surface accompanying AFM–FI transition.

The study of negative thermal expansion and magnetic evolution in antiperovskite compounds Cu0.8-xSnxMn0.2NMn3(0 ≤ x ≤ 0.3)

With increasing the substitution of Sn for Cu in Cu0.8-xSnxMn0.2NMn3, the initial cubic-tetragonal structural phase transition disappears for the samples x ≥ 0.10 and is replaced by a discontinuous lattice expansion with a cubic structure which has been confirmed by the measurements of variable temperature x-ray diffractions and specific heat. The discontinuous lattice expansion broadens with increasing the doping level x and the negative thermal expansion coefficient up to −64.54 ppm/K between 190 K and 235 K is found for the sample x = 0.3. Detailed magnetic measurements indicate that the magnetic ground state is meta-stable for the lower-doping level and transforms into spin-glass-like state owing to the enhancement of antiferromagnetic interaction when x is up to 0.3. Furthermore, the magnetization curves M(T) display abnormal behaviors for lower-x. For the samples x = 0.1 and 0.2, the jump of field-cooled magnetization curve MFC (defined as ΔMFC/MFC) around the lower-temperature magnetic transition i...

Understanding exceptional thermodynamic and kinetic stability of amorphous sulfur obtained by rapid compression

Amorphous sulfur (a-S) with excellent stability is obtained by rapid compression method. The prepared a-S has a single glassy phase and exhibits a wide supercooled liquid region of 112 K and much high thermal and kinetic stability at room temperature compared to that of conventional a-S fabricated by quenched method. The substantial improved thermal and kinetic stability is attributed to low energy state induced by rapid compressing process. The stable a-S is a model system for facilitating the studies of the nature of glasses and supercooled liquids.

Magnetically driven negative thermal expansion in antiperovskite Ga1-xMnxN0.8Mn3 (0.1 ≤ x ≤ 0.3)

Negative thermal expansion (NTE) was investigated for Ga1−xMnxN0.8Mn3 (0.1 ≤ x ≤ 0.3). As x increases, the temperature range where lattice contracts upon heating becomes broad and shifts to lower temperatures. The coefficient of linear thermal expansion beyond −40 ppm/K with a temperature interval of ∼50 K was obtained around room temperature in x = 0.2 and 0.25. Local lattice distortion which was thought to be intimately related to NTE is invisible in the X-ray pair distribution function of x = 0.3. Furthermore, a zero-field-cooling exchange bias was observed as a result of competing ferromagnetic (FM) and antiferromagnetic (AFM) orders. The concomitant FM order serves as an impediment to the growth of the AFM order, and thus broadens the temperature range of NTE. Our result suggests that NTE can be achieved in antiperovskite manganese nitrides by manipulating the magnetic orders without distorting the local structure.