Pis’ma v ZhETF, vol. 109, iss. 3, pp. 174 - 175

February 10

Vapor-phase synthesis and magnetoresistance of (Cd_1-xZn_x)₃As₂

(x = 0.007) single crystals

A. V. Kochura^a, L. N. Oveshnikov^b,c1), A. P. Kuzmenko^a, A. B. Davydov^c, S. Yu. Gavrilkin^c, V. S. Zakhvalinskii^d,

V. A. Kulbachinskii^b,e,f , N. A. Khokhlov^a, B. A. Aronzon^b,c

^aSouthwest State University, 305040 Kursk, Russia

^bNational Research Center “Kurchatov Institute”, 123182 Moscow, Russia

^cP.N. Lebedev Physical Institute, 119991 Moscow, Russia

^dBelgorod National Research University, 308015 Belgorod, Russia

^eLomonosov Moscow State University, 119991 Moscow, Russia

^fMoscow Institute of Physics and Technology (State University), 141700 Dolgoprudny, Russia

Submitted 27 November 2018

Resubmitted 27 November 2018

Accepted 28

November 2018

DOI: 10.1134/S0370274X1903007X

Further advancement of modern technologies in

(Cd_1-xZn_x)₃As₂ form a continuous range (0 ≤ x ≤ 1)

many respects depends on the materials with funda-

of solid solutions. The DSM-semimetal transition occurs

mentally new properties. The Dirac and Weyl semimet-

at some doping level x_c. However, the data concerning

als (DSM and WSM) are considered as such materi-

the value of x_c are quite ambiguous. This stimulates

als, having a tremendous potential for applications [1].

further studies of corresponding transition and prop-

These semimetals have inverted band structure with a

erties of (Cd_1-xZn_x)₃As₂ crystals. In this work we ap-

set of isolated Dirac points, where conduction and va-

plied vapor-phase method to grow (Cd_1-xZn_x)₃As₂ sin-

lence bands contact each other. The gapless electronic

gle crystals. We investigated the structure, surface mor-

states near these symmetry-protected Dirac points have

phology and transport properties (for transverse, B_⊥,

linear dispersion and rigidly coupled spin and momen-

and longitudinal, B_∥, magnetic field orientations) of ob-

tum directions. The latter is characterized by their chi-

tained samples. Here we present results for the sample

rality (C = ±1). A DSM system, such as Cd₃As₂, have

with x ≈ 0.007. This composition was confirmed by the

even number of Dirac points and doubly degenerate

energy-dispersive X-ray spectroscopy results (Zn - 0.42

bands (chiral degeneracy). These systems are considered

at.%, Cd - 59.38 at.%, and As - 40.2 at.%).

as a 3D graphene analogue, and therefore they are of

The electron diffraction pattern for studied

considerable interest for both fundamental science and

(Cd_0.993Zn_0.007)₃As₂ sample demonstrated high

applications.

crystalline quality of the crystal and the absence of

One of the difficulties in studies of Cd₃As₂ crystals

defects related to the Zn doping. The crystal lattice was

is that the DSM features in it are often suppressed due

found to be tetragonal with parameters a = 12.7Å and

to high bulk electron densities (related to high defect

c = 25.4Å (which agrees well with a = 12.6461Å and

formation rate). There are four polymorphic modifica-

c = 25.4378Å for α-Cd₃As₂ [4]). The surface of studied

tions of the Cd₃As₂ lattice - α, α^′, α^′′, and β. Con-

sample contain octahedron nuclei, which were earlier

ventional melt crystallization techniques are not suit-

observed during the synthesis of Cd₃As₂ nanostructures

able for the growth of high-quality Cd₃As₂ single crys-

from the vapor phase [5]. We also observed surface

tals due to the β → α^′′ phase transition, which leads

regions with pronounced step-like morphology, which,

to the formation of structural defects and to the in-

most likely, are formed by the {112} planes similarly to

crease in the charge carrier density. However, Cd₃As₂

α-Cd₃As₂ single crystals [5, 6]. In the Raman spectrum

crystals grown from the vapor phase at lower deposi-

of the sample, we observed two clearly pronounced

tion temperatures demonstrate higher crystalline qual-

peaks at

194

and 249 cm-1, and a weak peak at

ity. The electron density in Cd₃As₂ can be diminished by

292 cm^-1. Similar patterns were observed for micro-

a compensation doping, e.g., by Zn atoms [2, 3]. Crystals

and nanocrystals, as well as for single crystalline thin

films of Cd₃As₂ at room temperature

[7-10]. The

¹⁾e-mail: Oveshln@gmail.com

249 cm^-1 and 292 cm^-1 peaks, which we observed, do

174

Письма в ЖЭТФ том 109 вып. 3 - 4

2019

Vapor-phase synthesis and magnetoresistance of (Cd_1-xZn_x)₃As₂ (x = 0.007) single crystals

175

not correspond to the main oscillations of the lattice,

possible nesting of the Fermi-surface ellipsoids at some

but they are characteristic of the Cd₃As₂ and are

crystallographic directions.

usually associated with the presence of the defects

From the temperature dependence of the SdH oscil-

(Cd vacancies) and with the scattering of individual

lation amplitudes we evaluated effective mass of charge

phonons and collective plasmon modes by the Dirac

carriers m^∗ ≈ 0.033m_e (m_e is the free electron mass)

electron system [11].

in the investigated (Cd_0.993Zn_0.007)₃As₂ crystal. This

Magnetoresistance (MR) of (Cd_0.993Zn_0.007)₃As₂

value is in good agreement with m^∗ ≈ (0.023÷0.043)m_e

sample was measured at temperature T = 4.2 K for dif-

found for undoped Cd₃As₂ crystals [12]. We also es-

ferent magnetic field orientations and shown in Fig. 1.

timated corresponding electron density n_SdH ≈ 1.6 ×

We also observed clear Shubnikov-de Haas (SdH)

× 10¹⁸ cm^-3, taking into the account the four-fold de-

generacy of the Fermi surface in Cd₃As₂ crystal. Corre-

sponding carrier mobility is about 5.5 · 10⁴ cm²/(V· s).

This work was partially supported by the Rus-

sian Science Foundation (grant # 17-12-01345). Raman

spectroscopy studies, performed by A.P.Kuzmenko and

N.A. Khokhlov, were partially supported by the Min-

istry of Education and Science of the Russian Federation

(grant # 16.2814.2017/PCh).

Full text of the paper is published in JETP Letters

journal. DOI: 10.1134/S0021364019030019

N. P. Armitage, E. J. Mele, and A. Vishwanath, Rev.

Mod. Phys. 90(1), 015001 (2018).

E. K. Arushanov, Prog. Crystal. Growth. Charact 25(3),

131 (1992).

A. I. Belogorokhov, I. S. Zakharov, A. F. Knyazev, and

A. V. Kochura, Inorganic Materials 36(7), 653 (2000).

E. K. Arushanov, Prog. Crystal. Growth. Charact. 3(2-

3), 211 (1981).

C.-Z. Li, R. Zhu, X. Ke, J.-M. Zhang, L. X. Wang,

L. Zhang, Z.-M. Liao, and D.-P. Yu, Cryst. Growth De-

Fig. 1.

(Color online) The MR curves for

sign 15(7), 3264 (2015).

(Cd0.993Zn0.007)3As2 sample measured at

4.2

K for

M. N. Ali, Q. Gibson, S. Jeon, B. B. Zhou, A. Yazdani,

different magnetic field orientations. Inset shows the

and R. J. Cava, Inorganic Chemistry 53, 4062 (2014).

Fourier spectra of Shubnikov-de Haas oscillations for two

P. Schonher and T. Hesjedal, Appl. Phys. Lett. 106(1),

field orientations

013115 (2015).

oscillations. The background part of the transverse

K. Zhang, H. Pan, M. Zhang, Z. Wei, M. Gao, F. Song,

MR (R(B_⊥)) is linear for B > 1 T and rather huge

X. Wang, and R. Zhang, RSC Advances 7(29), 17689

(more than 150 %/T). The planar MR is non-linear

(2017).

and is about a half of the transverse MR. Linear MR

P. Cheng, C. Zhang, Y. Liu, X. Yuan, F. Song, Q. Sun,

in Cd₃As₂ crystals can appear due to weak inhomo-

P. Zhou, D. W. Zhang, and F. Xiu, New J. Phys 18(8),

geneities (such as As vacancies) leading to the fluc-

083003 (2016).

tuations of carrier mobilites [12]. This model suggest

10.

A. V. Kochura, S. F. Marenkin, A. I. Ril, A. L. Zhelud-

that such MR should demonstrate only weak anisotropy.

kevich, P. V. Abakumov, A. F. Knjazev, and M. B. Do-

Thus, the observed substantial anisotropy of MR in

bromyslov, J. Nano Electron. Phys. 7(4), 04079 (2015).

studied (Cd_0.993Zn_0.007)₃As₂ crystal is, most probably,

11.

A. Sharafeev, V. Gnezdilov, R. Sankar, F. C. Chou, and

P. Lemmens, Phys. Rev. B 95(23), 235148 (2017).

due to a chiral anomaly, resulting in negative MR con-

12.

A. Narayanan, M. D. Watson, S. F. Blake, N. Bruyant,

tribution [13]. The SdH oscillations also reveal pro-

L. Drigo, Y. L. Chen, D. Prabhakaran, B. Yan, C. Felser,

nounced anisotropy. Corresponding oscillations for the

T. Kong, P. C. Canfield, and A. I. Coldea, Phys. Rev.

B_⊥ demonstrate only a single frequency, while oscilla-

Lett. 114(11), 117201 (2015).

tions for B_∥ reveal more complicated behavior. The lat-

13.

H. Li, H. He, H.-Z. Lu, H. Zhang, H. Liu, R. Ma,

ter is related to the presence of two oscillation frequen-

Z. Fan, S.-Q. Shen, and J. Wang, Nature Comm. 7,

cies as it is suggested by corresponding Fourier spectra

10301 (2016).

(see inset in Fig. 1). This behavior is attributed to a

Письма в ЖЭТФ том 109 вып. 3 - 4

2019