Charge ordering phase submerged in ferromagnetic ordering phase in the Nd _0.5 Sr _0.5 MnO ₃ system

Abstract

In this letter, Nd0.5Sr0.5Mn1- xGaxO3 (0.0⩽x⩽0.075) manganites have been investigated. Diffuse satellite spots and streaks can be seen in transmission electron microscopy and the antiferromagnetic signal in electron spin resonance also occur early at 235 K which is much higher than the usually defined TCO of the Nd0.5Sr0.5Mn1- xGaxO3 sample, indicating that the charge ordering phase already appears in the ferromagnetic regions (TC=250 K). This charge ordering phase is submerged by the ferromagnetic phase so that it is invisible in routine measurements. As the TC moves to lower temperature with Ga doping, the charge ordering phase exhibits itself gradually around 240 K.

Anomalies of ultrasonic velocities, attenuation and elastic moduli in Nd 1− x Sr x MnO 3 perovskite manganite materials

“…The observed anomaly at T co has been reported already [28,29,31] in Nd 1Àx Sr x MnO 3 perovskite materials. The CO phenomenon in Nd 1Àx Sr x MnO 3 perovskite materials has a relatively narrow electron bandwidth [30].…”

Experimental evidence of coupling interaction between charge ordering and spin ordering

“…But in Ga-doped samples, the inflexion in the ρ-T curves can be observed around 240 K for all NSMGO samples, which is shown in the inset of Figure 1(a). In our previous reports, the temperature corresponding to this inflexion is CO temperature T CO [17], while T CO disappears in Cr-doped system. Figure 1(b) shows M-T curves under zero magnetic field cooling (ZFC) and magnetic field cooling (FC).…”

“…With decreasing temperature, the peak shifts to a higher field. Our previous work has proved that this peak is derived from the CO phase and also proved that CO phase always exists in Ga-doped samples by ESR spectra [17]. For NSMCO system, in the high temperature above T C , there is a Lorentzian lineshape absorption peak with a Lande factor g ∼2.0.…”

“…The experiments indicate that the ferromagnetic (FM) phase (T C is 250 K) and the A-type AFM phase coexist below 225 K in NSMO system, then the system enters into CO/CEtype antiferromagnetic (AFM) phase at 150 K [10][11][12][13][14][15][16]. As noted in previous work by our group, the charge ordering phase always exists in the Nd 0.5 Sr 0.5 Mn 1−x Ga x O 3 (0.0 x 0.075) system [17]. In this paper we choose Cr 3+ substitution for Mn 3+ and contrast Ga 3+ substitution for Mn 3+ in NSMO system because: a) the electronic configuration t 3 2g e 0 g of Cr 3+ ion is the same as that of Mn 4+ ; b) Both Cr and Ga ions should adopt the valence state trivalent when they are used to substituted Mn 3+ ions; c) Both Cr and Ga ions are no Jahn-Teller (JT) active ions and their radii are almost identical (61.5 pm for Cr 3+ compared to 62.0 pm for Ga 3+ ), so that the influence on the lattice will be identical; d) Since Ga 3+ also has a chemical stable electronic configuration, one can expect that it acts as a non-magnetic ion, while Cr 3+ is a magnetic ion with the electronic configuration t 3 2g e 0 g the same as that of Mn 4+ .…”

Effect of Cu doping and oxygen-annealing on the magnetic properties of Nd0.5Sr0.5Mn1−xCuxO3−δ (x = 0.0, 0.01, 0.03, 0.05 and 0.10)

“…Some other researchers also reported that the system enters into CO/CE-type antiferromagnetic (AFM) phase at 150 K [1,15,25e34]. But recently, Bo Hong et al reported T CO at 240 K and suggested that the temperature (w150 K) should be defined as T N only [35]. The ground state of NSMO is CO phase with a staggered orbital-order (OO) pattern of d 3xÀr 2 2 and d 3yÀr 2 2 , and CE-type AFM spin [28,33,36] [37].…”