The dividable curve reveals that the T c of the sample is above 300 K. Furthermore, there is no blocking temperature in this temperature range, indicating that the observed RTFM is an intrinsic attribute rather than caused by ferromagnetic impurities Cilengitide molecular weight [36, 37]. The M H curves for sample S1 measured at different temperatures from 10 to 300 K are shown in Figure 5b. The diamagnetic signal due to the sample holder was

subtracted, and the magnetization was saturated at about 3,000 Oe. It can be seen that the M s decreases with the increasing temperature. What’s more, the sample shows considerable hysteresis, and the coercive field decreases in a monotonic fashion from a value of 210 Oe at 10 K to 69 Oe at 300 K, which is a typical ferromagnetic behavior.

Figure 5 Magnetic characteristics of sphalerite CdS NSs represented by lines of different colors. (a) Room-temperature M-H curves of samples S1 to S4. The inset selleck chemicals llc shows ZFC and FC curves with a dc field of 100 Oe applied on sample S1. (b) M-H curves for sample S1 measured at different temperatures. (c) ESR spectra of sample S1 measured from 90 to 300 K. (d) The calculated ΔH which is H center is far from 321 mT (g = 2.0023) and the www.selleckchem.com/products/KU-55933.html variation of M s at different temperatures for the same sample (S1). ESR was performed to further characterize the magnetic properties of the sphalerite CdS NSs. Figure 5c depicts the ESR results measured 4��8C at different temperatures from 90 to 300 K for sample S1. It can be seen that the sample shows resonance signals with applied magnetic field from 0 to 500 mT. The center magnetic fields (H center) for the sample are far from 321 mT which characterize a free electron (g = 2.0023), indicating that the sample has obvious FM [38],

and the ferromagnetic coupling between the moments increase with the decreasing temperature. According to the theory of ferromagnetic resonance [38], the relationship between resonance field and microwave frequency in the ferromagnetic resonance is hν = gμ B · H, where h, ν, g, μ B, and H are the Planck constant, frequency of the applied microwave magnetic field, g-factor, Bohr magnetron, and resonance magnetic field, respectively. In FM materials, the orbital angular momentum quenching in the crystal field and g-factor is 2.0023; the resonance field is made up of applied field H a and magnetocrystalline anisotropy field H k: H = H a + H k. If we define H a as H and attribute the change of H k to the g-factor, which is defined as an effective g-factor (g eff), then the ferromagnetic resonance relationship changes to hν = g eff μ B · H a. H k will increase with the decreasing temperature, and then g eff will get higher. In sample S1, the g eff increases from 2.54 to 2.74 as the temperatures decrease from RT to 90 K.