Switching-on superparamagnetism in diluted magnetic Fe(III) doped CdSe quantum dots,CrystEngComm

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Switching-on superparamagnetism in diluted magnetic Fe(III) doped CdSe quantum dots
CrystEngComm ( IF 2.6 ) Pub Date : 2020/01/15 , DOI: 10.1039/c9ce01391a
Amar Nath Yadav _{1,

2,

3,

4} , Jasleen K. Bindra _{5,

6,

7,

8,

9} , Narendra Jakhar _{4,

10,

11,

12} , Kedar Singh _{1,

2,

3,

4}

Affiliation

Chemically prepared 0.5% iron (Fe) doped CdSe (Fe:CdSe) quantum dots (QDs) with a diameter of ∼3 nm and a wurtzite crystal structure are isolated. The oxidation state of Fe was confirmed by electron paramagnetic resonance (EPR) spectroscopy, from which it is evident that iron is in the Fe³⁺ oxidation state. The magnetic properties of Fe:CdSe QDs explored using a superconducting quantum interference device (SQUID) reveal multiple magnetic transitions. The DC magnetic susceptibility plot shows a low-temperature antiferromagnetism (AFM) transition observed below 25 K followed by another event occurring between 25 and ∼80 K. Further, the material shows superparamagnetic behaviour with a weak ferromagnetic exchange interaction as observed by field-dependent magnetization. At the lowest dopant concentration, we do not expect dopants to cluster or to form inclusions. Therefore, the observed magnetic behaviour is believed to be arising from the random substitution of the dopant ions and their magnetic exchange interaction with the CdSe host lattice.

中文翻译：

稀磁性Fe（III）掺杂的CdSe量子点中的开启超顺磁性

分离出化学制备的直径约3 nm的掺杂了0.5％铁（Fe）的CdSe（Fe：CdSe）量子点（QDs）和纤锌矿晶体结构。通过电子顺磁共振（EPR）光谱证实了Fe的氧化态，从中可以明显看出铁在Fe ^3+中氧化态。使用超导量子干涉仪（SQUID）探索的Fe：CdSe QD的磁性能揭示了多个磁跃迁。直流磁化率曲线显示在25 K以下观察到低温反铁磁性（AFM）转变，随后在25至〜80 K之间发生另一事件。此外，该材料显示出超顺磁行为，铁磁交换相互作用弱，通过磁场依赖观察到磁化。在最低的掺杂剂浓度下，我们预计掺杂剂不会聚集或形成夹杂物。因此，据信观察到的磁行为是由于掺杂离子的随机取代以及它们与CdSe主晶格的磁交换相互作用而引起的。

更新日期：2020-03-09

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