Temperature and Magnetic Field-Assisted Switching of Magnetization and Observation of Exchange Bias in YbCrO₃ Nanocrystals

Abstract

In this paper, we demonstrate an interesting feature in YbCrO3 (YCO) nanocrystals, in which the material shows temperature and external magnetic field-assisted switching (a complete sign reversal) of zero field cooled magnetization (MZFC) and observation of exchange bias (EB) as a result of competing spin interaction at low temperature. This feature can be applied in nonvolatile memories, where, simply by changing the magnitude of the Hext and T, the polarity of the magnetization can be switched between negative and positive. We also observed negative magnetization in YCO. Our results showed that, below its Nèel temperature (TN ≈ 119 K), the MZFC crosses over to negative sign for H < 1000 Oe. At 60 K, YCO showed a significant negative MZFC ≈ -0.05 emu/g (at 100 Oe) due to the competing effects of Yb(3+), Cr(3+) spins, thermal activation energy, and Hext. At further lower temperatures, the MZFC showed a crossover to positive values, and the crossover temperature showed the dependence on Hext (∼19 K for 100 Oe curve). The YCO also showed Hext and T-dependent HEB, which changed its sign with T. The observed T-dependent sign reversal in the EB was closely associated with the sign reversal of MZFC. The symmetric shift in field-cooled isothermal hysteresis curves confirmed that the observed EB was not due to the unsaturated minor loop. The training cycle further confirmed that the HEB value decreased to ∼2% of the initial value of observed EB, which was very small compared to the observed HEB in YCO, which indicated stable spin configuration at the locally formed ferromagnetic/antiferromagnetic interface.

Structural, magnetic, magnetocaloric and specific heat investigations on Mn doped PrCrO3orthochromites

“…They also show the temperature induced magnetization reversal (i.e. the magnetization changes its polarity from positive to negative at one par ticular temperature known as compensation temperature) and spin reorientation transition at low temperatures (below 50 K) [3,4,8,11]. Below the Neel temperature, the spins of nearest Cr 3+ ions do not possess the perfect antiparallel configuration, therefore, net magnetization is not zero and along with antiferromagnetic behaviour one observes weak ferromagnetic component also.…”

“…Perovskite orthochromites are very promising materials for thermomagnetic switches, spintronic and thermally assisted magnetic random access memory (TAMRAM) devices [1][2][3][4]. Their general chemical formula is RCrO 3 (R = rare earth or yttrium ion) having distorted orthorhombic structure (Pnma space group) and they exhibit canted antiferromagnetism in the G-type configuration below the Neel temperature (T N ) in the range 112-282 K which depends upon the ionic size of the tri-valent rare-earth ion present [5][6][7][8][9][10].…”

“…Whenever the applied magnetic field becomes greater than the internal field produced by chromium ions, the magnetization flipping along the field direction takes place resulting in the positive magnetization over the measurement range of temper ature [4]. So far, many orthochromites like YCrO 3 [12][13][14], LaCrO 3 [15], CeCrO 3 [3,16], PrCrO 3 [17][18][19], NdCrO 3 [20,21], SmCrO 3 [22][23][24], GdCrO 3 [25,26], DyCrO 3 [27,28], YbCrO 3 [4,29] and HoCrO 3 [30,31] have been investigated for their complex magnetic properties and interesting results have been reported on them. As far as the PrCrO 3 (PCO) orthochromite is concerned, only a very few studies exist on it [17][18][19].…”

The tunable spin reorientation, temperature induced magnetization reversal, and spontaneous exchange bias effect of Sm0.7Y0.3Cr1−xGaxO3

“…Most reported TIMR effect from positive to negative occurs in FC mode while few in ZFC mode. 2,10,25,[38][39][40][41][42] Here, the TIMR effect observed in ZFC mode shows dependence on doping concentration and the compensation temperature for x ¼ 0.2 and 0.3 is at near 74 K and almost the same, indicating its intrinsic feature.…”

Observation of magnetization reversal behavior in Sm0.9Gd0.1Cr0.85Mn0.15O3 orthochromites

“…[1][2][3][4][5] This is useful in thermomagnetic switches and thermally assisted random access memories. 6,7 TIMR is defined as a temperature induced crossover of magnetization from a positive to negative value. It has also been reported in other compounds viz.…”