Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (10): 2495-2502.

• ARTICLE •

### Silicon Bridge-Tuned Electronic Structures and Transport Properties of Polymetallocenes

Lei PEI,Gui-Ling ZHANG*(),Yan SHANG,Cui-Cui SUN,Tian GAN

• Received:2016-04-05 Published:2016-09-30
• Contact: Gui-Ling ZHANG E-mail:guiling-002@163.com
• Supported by:
The project was supported by the National Natural Science Foundation of China(51473042)

Abstract:

Silicon bridge-tuned electronic structures and transport properties of polymetallocenes,[V(Cp)2(SiH2)n]m (n=1 (a), n=2 (b), n=3 (c); m=∞; Cp=cyclopentadienyl), are studied using the densityfunctional theory (DFT) and non-equilibrium Green's function (NEGF) methods. As the silicon bridge islengthened, the V-V ferromagnetic (FM) coupling is weakened, while the antiferromagnetic (AFM) coupling isstrengthened. Polymetallocenes a and b favor the FM ground state, while c prefers the AFM ground state. EachV atom in the FM state of a and b has a magnetic moment of ~3.0μB, three times larger than that in the Vbenzeneor V-cyclopentadiene multidecker complex. The transport properties of a-c are in good agreementwith their electronic structures. Their conductivities follow the sequence c > b > a. For a and b, the spin-downstate has slightly higher conductivity than the spin-up state. Polymetallocenes a and c can both display evidentnegative differential resistance (NDR) behavior, while b cannot. This difference may originate from theorientation of the two V(Cp)2 units, which is V-shaped for a and c (odd number of SiH2 units), leading to ioniclikeinter-quantum dot coupling, and parallel for b (even number of SiH2 units), leading to covalent-like interquantumdot coupling. In addition, the conductivity of a-c is sensitive to the current direction because of theasymmetric coupling between the scattering region and two electrodes.

MSC2000:

• O641